---
title: "POST /v1/billing.preview_update"
method: POST
path: "/v1/billing.preview_update"
tags: ["billing"]
---

# POST /v1/billing.preview_update

`POST /v1/billing.preview_update`

Previews the billing changes that would occur when updating a subscription, without actually making any changes.

Use this endpoint to show customers prorated charges or refunds before confirming subscription modifications.

## Headers

- `x-api-version` string, required

## Request body

- object
  - `customer_id` string, required — The ID of the customer to attach the plan to.
  - `entity_id` string — The ID of the entity to attach the plan to.
  - `plan_id` string — The ID of the plan to update. Optional if subscription_id is provided, or if the customer has only one product.
  - `feature_quantities` object[] — If this plan contains prepaid features, use this field to specify the quantity of each prepaid feature. This quantity includes the included amount and billing units defined when setting up the plan.
    - `feature_id` string, required — The ID of the feature to set quantity for.
    - `quantity` number — The quantity of the feature.
    - `adjustable` boolean — Whether the customer can adjust the quantity.
  - `version` number — The version of the plan to attach.
  - `customize` object — Customize the plan to attach. Can override the price, items, licenses, free trial, or a combination.
    - `price` object, nullable — Base price configuration for a plan.
      - `amount` number, required — Base price amount for the plan.
      - `interval` 'one_off' | 'week' | 'month' | 'quarter' | 'semi_annual' | 'year', required — Billing interval (e.g. 'month', 'year').
      - `interval_count` number — Number of intervals per billing cycle. Defaults to 1.
      - `additional_currencies` object[] — Base price amounts in additional currencies. The base 'amount' is in the org's default currency.
        - `currency` string, required — Three-letter Stripe-supported currency code (e.g. 'eur', 'gbp').
        - `amount` number, required — Price amount in this currency. Set explicitly per currency, not converted from the base amount.
    - `items` object[] — Override the items in the plan (PUT-style — replaces all existing items). Mutually exclusive with add_items / remove_items / deprecated update_items.
      - `feature_id` string, required — The ID of the feature to configure.
      - `included` number — Number of free units included. Balance resets to this each interval for consumable features.
      - `unlimited` boolean — If true, customer has unlimited access to this feature.
      - `reset` object — Reset configuration for consumable features. Omit for non-consumable features like seats.
        - `interval` 'one_off' | 'minute' | 'hour' | 'day' | 'week' | 'month' | 'quarter' | 'semi_annual' | 'year', required — Interval at which balance resets (e.g. 'month', 'year'). For consumable features only.
        - `interval_count` number — Number of intervals between resets. Defaults to 1.
      - `price` object — Pricing for usage beyond included units. Omit for free features.
        - `amount` number — Price per billing_units after included usage. Either 'amount' or 'tiers' is required.
        - `additional_currencies` object[] — Amounts in additional currencies for this flat price. The base 'amount' is in the org's default currency. Only valid with 'amount', not 'tiers'.
          - `currency` string, required — Three-letter Stripe-supported currency code (e.g. 'eur', 'gbp').
          - `amount` number, required — Price amount in this currency. Set explicitly per currency, not converted from the base amount.
        - `tiers` object[] — Tiered pricing. Either 'amount' or 'tiers' is required.
          - `to` union, required
            - number
            - 'inf'
          - `amount` number
          - `flat_amount` number
          - `additional_currencies` object[] — Per-currency amounts for this tier. Tier boundaries ('to') are shared across all currencies.
            - `currency` string, required — Three-letter Stripe-supported currency code (e.g. 'eur', 'gbp').
            - `amount` number — Per-unit amount for this tier in this currency.
            - `flat_amount` number — Flat amount for this tier in this currency, if the tier uses one.
        - `tier_behavior` 'graduated' | 'volume'
        - `interval` 'one_off' | 'week' | 'month' | 'quarter' | 'semi_annual' | 'year', required — Billing interval. For consumable features, should match reset.interval.
        - `interval_count` number — Number of intervals per billing cycle. Defaults to 1.
        - `billing_units` number — Units per price increment. Usage is rounded UP when billed (e.g. billing_units=100 means 101 rounds to 200).
        - `billing_method` 'prepaid' | 'usage_based', required — 'prepaid' for upfront payment (seats), 'usage_based' for pay-as-you-go.
        - `max_purchase` number, nullable — Max units purchasable beyond included. E.g. included=100, max_purchase=300 allows 400 total. Null for no limit.
      - `proration` object — Proration settings for prepaid features. Controls mid-cycle quantity change billing.
        - `on_increase` 'bill_immediately' | 'prorate_immediately' | 'prorate_next_cycle' | 'bill_next_cycle', required — Billing behavior when quantity increases mid-cycle.
        - `on_decrease` 'prorate' | 'prorate_immediately' | 'prorate_next_cycle' | 'none' | 'no_prorations', required — Credit behavior when quantity decreases mid-cycle.
      - `rollover` object — Rollover config for unused units. If set, unused included units carry over.
        - `max` number — Max rollover units. Omit for unlimited rollover.
        - `max_percentage` number — Maximum rollover as a percentage (0-100) of included + prepaid grant. Mutually exclusive with max.
        - `expiry_duration_type` 'month' | 'forever', required — When rolled over units expire.
        - `expiry_duration_length` number — Number of periods before expiry.
    - `add_items` object[] — Items to add to the plan.
      - `feature_id` string, required — The ID of the feature to configure.
      - `included` number — Number of free units included. Balance resets to this each interval for consumable features.
      - `unlimited` boolean — If true, customer has unlimited access to this feature.
      - `reset` object — Reset configuration for consumable features. Omit for non-consumable features like seats.
        - `interval` 'one_off' | 'minute' | 'hour' | 'day' | 'week' | 'month' | 'quarter' | 'semi_annual' | 'year', required — Interval at which balance resets (e.g. 'month', 'year'). For consumable features only.
        - `interval_count` number — Number of intervals between resets. Defaults to 1.
      - `price` object — Pricing for usage beyond included units. Omit for free features.
        - `amount` number — Price per billing_units after included usage. Either 'amount' or 'tiers' is required.
        - `additional_currencies` object[] — Amounts in additional currencies for this flat price. The base 'amount' is in the org's default currency. Only valid with 'amount', not 'tiers'.
          - `currency` string, required — Three-letter Stripe-supported currency code (e.g. 'eur', 'gbp').
          - `amount` number, required — Price amount in this currency. Set explicitly per currency, not converted from the base amount.
        - `tiers` object[] — Tiered pricing. Either 'amount' or 'tiers' is required.
          - `to` union, required
            - number
            - 'inf'
          - `amount` number
          - `flat_amount` number
          - `additional_currencies` object[] — Per-currency amounts for this tier. Tier boundaries ('to') are shared across all currencies.
            - `currency` string, required — Three-letter Stripe-supported currency code (e.g. 'eur', 'gbp').
            - `amount` number — Per-unit amount for this tier in this currency.
            - `flat_amount` number — Flat amount for this tier in this currency, if the tier uses one.
        - `tier_behavior` 'graduated' | 'volume'
        - `interval` 'one_off' | 'week' | 'month' | 'quarter' | 'semi_annual' | 'year', required — Billing interval. For consumable features, should match reset.interval.
        - `interval_count` number — Number of intervals per billing cycle. Defaults to 1.
        - `billing_units` number — Units per price increment. Usage is rounded UP when billed (e.g. billing_units=100 means 101 rounds to 200).
        - `billing_method` 'prepaid' | 'usage_based', required — 'prepaid' for upfront payment (seats), 'usage_based' for pay-as-you-go.
        - `max_purchase` number, nullable — Max units purchasable beyond included. E.g. included=100, max_purchase=300 allows 400 total. Null for no limit.
      - `proration` object — Proration settings for prepaid features. Controls mid-cycle quantity change billing.
        - `on_increase` 'bill_immediately' | 'prorate_immediately' | 'prorate_next_cycle' | 'bill_next_cycle', required — Billing behavior when quantity increases mid-cycle.
        - `on_decrease` 'prorate' | 'prorate_immediately' | 'prorate_next_cycle' | 'none' | 'no_prorations', required — Credit behavior when quantity decreases mid-cycle.
      - `rollover` object — Rollover config for unused units. If set, unused included units carry over.
        - `max` number — Max rollover units. Omit for unlimited rollover.
        - `max_percentage` number — Maximum rollover as a percentage (0-100) of included + prepaid grant. Mutually exclusive with max.
        - `expiry_duration_type` 'month' | 'forever', required — When rolled over units expire.
        - `expiry_duration_length` number — Number of periods before expiry.
    - `remove_items` object[] — Filters selecting items to remove from the plan.
      - `feature_id` string — Match items linked to this feature.
      - `billing_method` 'prepaid' | 'usage_based' — Match items with this billing method (prepaid or usage_based).
      - `interval` union — Match items with this interval. Accepts either a BillingInterval (price-side) or a ResetInterval (reset-side, includes day/hour/minute) so price-less items keyed by reset.interval can be disambiguated.
        - 'one_off' | 'week' | 'month' | 'quarter' | 'semi_annual' | 'year'
        - 'one_off' | 'minute' | 'hour' | 'day' | 'week' | 'month' | 'quarter' | 'semi_annual' | 'year'
      - `interval_count` integer — Match items with this interval_count. Disambiguates between items that share an interval but differ in count.
    - `free_trial` object, nullable — Free trial configuration for a plan.
      - `duration_length` number, required — Number of duration_type periods the trial lasts.
      - `duration_type` 'day' | 'month' | 'year' — Unit of time for the trial ('day', 'month', 'year').
      - `card_required` boolean — If true, payment method required to start trial. Customer is charged after trial ends.
      - `on_end` 'bill' | 'revert' — Behavior when the trial ends. 'bill' charges the customer (default). 'revert' expires the trial and restores the customer's previous plan.
    - `billing_controls` object — Override the plan's billing controls (auto top-ups, spend limits, usage limits, usage alerts, overage allowed) for this customer.
      - `auto_topups` object[] — List of auto top-up configurations per feature.
        - `feature_id` string, required — The ID of the feature (credit balance) to auto top-up.
        - `enabled` boolean — Whether auto top-up is enabled.
        - `threshold` number, required — When the balance drops below this threshold, an auto top-up will be purchased.
        - `quantity` number, required — Amount of credits to add per auto top-up.
        - `purchase_limit` object — Optional rate limit to cap how often auto top-ups occur. Pass count to set the current window's consumed top-ups.
          - `interval` 'hour' | 'day' | 'week' | 'month', required — The time interval for the purchase limit window.
          - `interval_count` number — Number of intervals in the purchase limit window.
          - `limit` number, required — Maximum number of auto top-ups allowed within the interval.
          - `count` number — Set the current window's consumed auto top-up count. Omit to leave runtime state unchanged.
        - `invoice_mode` boolean — When true, auto top-up creates a send_invoice invoice instead of auto-charging.
      - `spend_limits` object[] — List of overage spend limits per feature (caps overage spend).
        - `feature_id` string — Optional feature ID this spend limit applies to.
        - `enabled` boolean — Whether the overage spend limit is enabled.
        - `limit_type` 'absolute' | 'usage_percentage' — How overage_limit is interpreted: an absolute overage cap (default) or a percentage of the main-plan allowance.
        - `overage_limit` number — Overage cap for the feature: absolute units, or a percent (e.g. 120) when limit_type is usage_percentage.
        - `skip_overage_billing` boolean — When true, overage for this feature is not posted to Stripe. Usage tracking and balance resets still behave normally.
      - `usage_limits` object[] — List of hard usage caps per feature (max units per interval).
        - `feature_id` string, required — The feature this usage limit applies to.
        - `enabled` boolean — Whether this usage limit is enabled.
        - `limit` number, required — Maximum units allowed per interval.
        - `interval` 'day' | 'week' | 'month' | 'year', required — Interval for the cap, aligned to the customer's billing cycle.
        - `filter` object — When set, only usage from events whose properties match counts toward this cap. Omit to count all usage of the feature.
          - `properties` object, required
      - `usage_alerts` object[] — List of usage alert configurations per feature.
        - `feature_id` string — The feature ID this alert applies to.
        - `enabled` boolean — Whether this usage alert is enabled.
        - `threshold` number, required — The threshold value that triggers the alert. For usage or remaining, this is an absolute count. For usage_percentage or remaining_percentage, this is a percentage (0-100).
        - `threshold_type` 'usage' | 'usage_percentage' | 'remaining' | 'remaining_percentage', required — Whether the threshold is an absolute count or a percentage of the usage allowance or remaining balance.
        - `name` string — Optional user-defined label to distinguish multiple alerts on the same feature.
      - `overage_allowed` object[] — List of overage allowed controls per feature. When enabled, usage can exceed balance.
        - `feature_id` string, required — The feature ID this overage allowed control applies to.
        - `enabled` boolean — Whether overage is allowed for this feature.
    - `upsert_licenses` object[] — License links to add or override for this customer, keyed by license_plan_id. Omitted fields inherit the plan catalog link (included defaults to 1 when the license is not in the catalog). A bare entry restores the license to pure catalog inheritance.
      - `license_plan_id` string, required
      - `included` integer
      - `prepaid_only` boolean
      - `customize` object, nullable
        - `price` object, nullable — Base price configuration for a plan.
          - `amount` number, required — Base price amount for the plan.
          - `interval` 'one_off' | 'week' | 'month' | 'quarter' | 'semi_annual' | 'year', required — Billing interval (e.g. 'month', 'year').
          - `interval_count` number — Number of intervals per billing cycle. Defaults to 1.
          - `additional_currencies` object[] — Base price amounts in additional currencies. The base 'amount' is in the org's default currency.
            - `currency` string, required — Three-letter Stripe-supported currency code (e.g. 'eur', 'gbp').
            - `amount` number, required — Price amount in this currency. Set explicitly per currency, not converted from the base amount.
        - `add_items` object[]
          - `feature_id` string, required — The ID of the feature to configure.
          - `included` number — Number of free units included. Balance resets to this each interval for consumable features.
          - `unlimited` boolean — If true, customer has unlimited access to this feature.
          - `reset` object — Reset configuration for consumable features. Omit for non-consumable features like seats.
            - `interval` 'one_off' | 'minute' | 'hour' | 'day' | 'week' | 'month' | 'quarter' | 'semi_annual' | 'year', required — Interval at which balance resets (e.g. 'month', 'year'). For consumable features only.
            - `interval_count` number — Number of intervals between resets. Defaults to 1.
          - `price` object — Pricing for usage beyond included units. Omit for free features.
            - `amount` number — Price per billing_units after included usage. Either 'amount' or 'tiers' is required.
            - `additional_currencies` object[] — Amounts in additional currencies for this flat price. The base 'amount' is in the org's default currency. Only valid with 'amount', not 'tiers'.
              - …
            - `tiers` object[] — Tiered pricing. Either 'amount' or 'tiers' is required.
              - …
            - `tier_behavior` 'graduated' | 'volume'
            - `interval` 'one_off' | 'week' | 'month' | 'quarter' | 'semi_annual' | 'year', required — Billing interval. For consumable features, should match reset.interval.
            - `interval_count` number — Number of intervals per billing cycle. Defaults to 1.
            - `billing_units` number — Units per price increment. Usage is rounded UP when billed (e.g. billing_units=100 means 101 rounds to 200).
            - `billing_method` 'prepaid' | 'usage_based', required — 'prepaid' for upfront payment (seats), 'usage_based' for pay-as-you-go.
            - `max_purchase` number, nullable — Max units purchasable beyond included. E.g. included=100, max_purchase=300 allows 400 total. Null for no limit.
          - `proration` object — Proration settings for prepaid features. Controls mid-cycle quantity change billing.
            - `on_increase` 'bill_immediately' | 'prorate_immediately' | 'prorate_next_cycle' | 'bill_next_cycle', required — Billing behavior when quantity increases mid-cycle.
            - `on_decrease` 'prorate' | 'prorate_immediately' | 'prorate_next_cycle' | 'none' | 'no_prorations', required — Credit behavior when quantity decreases mid-cycle.
          - `rollover` object — Rollover config for unused units. If set, unused included units carry over.
            - `max` number — Max rollover units. Omit for unlimited rollover.
            - `max_percentage` number — Maximum rollover as a percentage (0-100) of included + prepaid grant. Mutually exclusive with max.
            - `expiry_duration_type` 'month' | 'forever', required — When rolled over units expire.
            - `expiry_duration_length` number — Number of periods before expiry.
        - `remove_items` object[]
          - `feature_id` string — Match items linked to this feature.
          - `billing_method` 'prepaid' | 'usage_based' — Match items with this billing method (prepaid or usage_based).
          - `interval` union — Match items with this interval. Accepts either a BillingInterval (price-side) or a ResetInterval (reset-side, includes day/hour/minute) so price-less items keyed by reset.interval can be disambiguated.
            - 'one_off' | 'week' | 'month' | 'quarter' | 'semi_annual' | 'year'
            - 'one_off' | 'minute' | 'hour' | 'day' | 'week' | 'month' | 'quarter' | 'semi_annual' | 'year'
          - `interval_count` integer — Match items with this interval_count. Disambiguates between items that share an interval but differ in count.
      - `metadata` object
  - `invoice_mode` object — Invoice mode creates a draft or open invoice and sends it to the customer, instead of charging their card immediately. This uses Stripe's send_invoice collection method.
    - `enabled` boolean, required — When true, creates an invoice and sends it to the customer instead of charging their card immediately. Uses Stripe's send_invoice collection method.
    - `enable_plan_immediately` boolean — If true, enables the plan immediately even though the invoice is not paid yet.
    - `finalize` boolean — If true, finalizes the invoice so it can be sent to the customer. If false, keeps it as a draft for manual review.
    - `invoice_template_id` string — ID of an invoice template (configured in billing settings) whose footer (e.g. bank details) is applied to the invoice.
    - `net_terms_days` integer — Number of days the customer has to pay the invoice before it is due (Stripe days_until_due).
  - `proration_behavior` 'prorate_immediately' | 'none' — How to handle proration when updating an existing subscription. 'prorate_immediately' charges/credits prorated amounts now, 'none' skips creating any charges.
  - `redirect_mode` 'always' | 'if_required' | 'never' — Controls when to return a checkout URL. 'always' returns a URL even if payment succeeds, 'if_required' only when payment action is needed, 'never' disables redirects.
  - `subscription_id` string — A unique ID to identify this subscription. Can be used to target specific subscriptions in update operations when a customer has multiple products with the same plan.
  - `discounts` object[] — List of discounts to apply. Each discount can be an Autumn reward ID, Stripe coupon ID, or Stripe promotion code.
    - `reward_id` string — The ID of the reward to apply as a discount.
    - `promotion_code` string — The promotion code to apply as a discount.
  - `cancel_action` 'cancel_immediately' | 'cancel_end_of_cycle' | 'uncancel' — Action to perform for cancellation. 'cancel_immediately' cancels now with prorated refund, 'cancel_end_of_cycle' cancels at period end, 'uncancel' reverses a pending cancellation.
  - `billing_cycle_anchor` 'now' — Reset the billing cycle anchor immediately with 'now'
  - `no_billing_changes` boolean — If true, the subscription is updated internally without applying billing changes in Stripe.
  - `refund_last_payment` 'prorated' | 'full' — Controls how the last payment is refunded on immediate cancellation. 'prorated' refunds the unused portion, 'full' refunds the entire last payment.
  - `recalculate_balances` object — Controls whether balances should be recalculated during the subscription update.
    - `enabled` boolean, required — If true, recalculates balances during the subscription update. Only applicable when updating feature quantities.
  - `carry_over_usages` object — Whether to carry over usages from the previous plan.
    - `enabled` boolean, required — Whether to carry over usages from the previous plan.
    - `feature_ids` string[] — The IDs of the features to carry over usages for. If left undefined, all consumable features will be carried over.
  - `license_quantities` object[] — Total seat quantities (inclusive of the license's included count) per license plan offered by this plan. Licenses not listed keep their current paid quantity.
    - `license_plan_id` string, required — The license plan to set seat quantity for.
    - `quantity` integer, required — Total seats for the license, inclusive of the plan's included amount — seats beyond it are paid.

## Response `200`

OK

- object
  - `customer_id` string, required — The ID of the customer.
  - `line_items` object[], required — List of line items for the current billing period.
    - `display_name` string, required — The name of the line item to display to the customer if you're building a UI. It will either be the plan name or the feature name.
    - `description` string, required — A detailed description of the line item.
    - `subtotal` number, required — The amount in cents before discounts and tax for this line item.
    - `total` number, required — The final amount in cents after discounts and tax for this line item.
    - `discounts` object[] — List of discounts applied to this line item.
      - `amount_off` number, required
      - `percent_off` number
      - `reward_id` string
      - `reward_name` string
    - `plan_id` string, required — The ID of the plan that this line item belongs to.
    - `feature_id` string, nullable, required — The ID of the feature that this line item belongs to.
    - `period` object — The period of time that this line item is being charged for.
      - `start` number, required — The start of the period in milliseconds since the Unix epoch.
      - `end` number, required — The end of the period in milliseconds since the Unix epoch.
    - `quantity` number, required — The quantity of the line item.
  - `subtotal` number, required — The total amount in cents before discounts and tax for the current billing period.
  - `total` number, required — The final amount in cents after discounts and tax for the current billing period.
  - `currency` string, required — The three-letter ISO currency code (e.g., 'usd').
  - `next_cycle` object — Preview of the next billing cycle, if applicable. This shows what the customer will be charged in subsequent cycles.
    - `starts_at` number, required — Unix timestamp (milliseconds) when the next billing cycle starts.
    - `subtotal` number, required — The total amount in cents before discounts and tax for the next cycle.
    - `total` number, required — The final amount in cents after discounts and tax for the next cycle.
    - `line_items` object[], required — List of line items for the next billing cycle.
      - `display_name` string, required — The name of the line item to display to the customer if you're building a UI. It will either be the plan name or the feature name.
      - `description` string, required — A detailed description of the line item.
      - `subtotal` number, required — The amount in cents before discounts and tax for this line item.
      - `total` number, required — The final amount in cents after discounts and tax for this line item.
      - `discounts` object[] — List of discounts applied to this line item.
        - `amount_off` number, required
        - `percent_off` number
        - `reward_id` string
        - `reward_name` string
      - `plan_id` string, required — The ID of the plan that this line item belongs to.
      - `feature_id` string, nullable, required — The ID of the feature that this line item belongs to.
      - `period` object — The period of time that this line item is being charged for.
        - `start` number, required — The start of the period in milliseconds since the Unix epoch.
        - `end` number, required — The end of the period in milliseconds since the Unix epoch.
      - `quantity` number, required — The quantity of the line item.
    - `usage_line_items` object[], required — List of line items for usage-based features in the next cycle.
      - `display_name` string, required — The name of the line item to display to the customer if you're building a UI. It will either be the plan name or the feature name.
      - `plan_id` string, required — The ID of the plan that this line item belongs to.
      - `feature_id` string, nullable, required — The ID of the feature that this line item belongs to.
      - `period` object — The period of time that this line item is being charged for.
        - `start` number, required — The start of the period in milliseconds since the Unix epoch.
        - `end` number, required — The end of the period in milliseconds since the Unix epoch.
  - `expand` string[] — Expand the response with additional data.
  - `incoming` object[], required — Products or subscription changes being added or updated.
    - `plan_id` string, required — The ID of the plan affected by this preview change.
    - `plan` Plan
      - `id` string, required — Unique identifier for the plan.
      - `name` string, required — Display name of the plan.
      - `description` string, nullable, required — Optional description of the plan.
      - `group` string, nullable, required — Group identifier for organizing related plans. Plans in the same group are mutually exclusive.
      - `version` number, required — Version number of the plan. Incremented when plan configuration changes.
      - `add_on` boolean, required — Whether this is an add-on plan that can be attached alongside a main plan.
      - `auto_enable` boolean, required — If true, this plan is automatically attached when a customer is created. Used for free plans.
      - `price` object, nullable, required — Base recurring price for the plan. Null for free plans or usage-only plans.
        - `amount` number, required — Base price amount for the plan.
        - `additional_currencies` object[] — Base price amounts in additional currencies. The base 'amount' is in the org's default currency.
          - `currency` string, required — Three-letter Stripe-supported currency code (e.g. 'eur', 'gbp').
          - `amount` number, required — Price amount in this currency. Set explicitly per currency, not converted from the base amount.
        - `interval` 'one_off' | 'week' | 'month' | 'quarter' | 'semi_annual' | 'year', required — Billing interval (e.g. 'month', 'year').
        - `interval_count` number — Number of intervals per billing cycle. Defaults to 1.
        - `display` object — Display text for showing this price in pricing pages.
          - `primary_text` string, required — Main display text (e.g. '$10' or '100 messages').
          - `secondary_text` string — Secondary display text (e.g. 'per month' or 'then $0.5 per 100').
      - `items` object[], required — Feature configurations included in this plan. Each item defines included units, pricing, and reset behavior for a feature.
        - `feature_id` string, required — The ID of the feature this item configures.
        - `feature` object — The full feature object if expanded.
          - `id` string, required — The ID of the feature, used to refer to it in other API calls like /track or /check.
          - `name` string, nullable — The name of the feature.
          - `type` 'static' | 'boolean' | 'single_use' | 'continuous_use' | 'credit_system' | 'ai_credit_system', required — The type of the feature
          - `display` object, nullable — Singular and plural display names for the feature.
            - `singular` string, required — The singular display name for the feature.
            - `plural` string, required — The plural display name for the feature.
          - `credit_schema` object[], nullable — Credit cost schema for credit system features.
            - `metered_feature_id` string, required — The ID of the metered feature (should be a single_use feature).
            - `credit_cost` number, required — The credit cost of the metered feature.
          - `archived` boolean, nullable — Whether or not the feature is archived.
        - `included` number, required — Number of free units included. For consumable features, balance resets to this number each interval.
        - `unlimited` boolean, required — Whether the customer has unlimited access to this feature.
        - `reset` object, nullable, required — Reset configuration for consumable features. Null for non-consumable features like seats where usage persists across billing cycles.
          - `interval` 'one_off' | 'minute' | 'hour' | 'day' | 'week' | 'month' | 'quarter' | 'semi_annual' | 'year', required — The interval at which the feature balance resets (e.g. 'month', 'year'). For consumable features, usage resets to 0 and included units are restored.
          - `interval_count` number — Number of intervals between resets. Defaults to 1.
        - `price` object, nullable, required — Pricing configuration for usage beyond included units. Null if feature is entirely free.
          - `amount` number — Price per billing_units after included usage is consumed. Mutually exclusive with tiers.
          - `additional_currencies` object[] — Amounts in additional currencies for this flat price. The base 'amount' is in the org's default currency. Only valid with 'amount', not 'tiers' (tiered prices carry per-currency amounts on each tier).
            - `currency` string, required — Three-letter Stripe-supported currency code (e.g. 'eur', 'gbp').
            - `amount` number, required — Price amount in this currency. Set explicitly per currency, not converted from the base amount.
          - `tiers` object[] — Tiered pricing configuration. Each tier's 'to' INCLUDES the included amount. Either 'tiers' or 'amount' is required.
            - `to` union, required
              - …
            - `amount` number, required
            - `flat_amount` number
            - `additional_currencies` object[]
              - …
          - `tier_behavior` 'graduated' | 'volume'
          - `interval` 'one_off' | 'week' | 'month' | 'quarter' | 'semi_annual' | 'year', required — Billing interval for this price. For consumable features, should match reset.interval.
          - `interval_count` number — Number of intervals per billing cycle. Defaults to 1.
          - `billing_units` number, required — Number of units per price increment. Usage is rounded UP to the nearest billing_units when billed (e.g. billing_units=100 means 101 usage rounds to 200).
          - `billing_method` 'prepaid' | 'usage_based', required — 'prepaid' for features like seats where customers pay upfront, 'usage_based' for pay-as-you-go after included usage.
          - `max_purchase` number, nullable, required — Maximum units a customer can purchase beyond included. E.g. if included=100 and max_purchase=300, customer can use up to 400 total before usage is capped. Null for no limit.
        - `display` object — Display text for showing this item in pricing pages.
          - `primary_text` string, required — Main display text (e.g. '$10' or '100 messages').
          - `secondary_text` string — Secondary display text (e.g. 'per month' or 'then $0.5 per 100').
        - `rollover` object — Rollover configuration for unused units. If set, unused included units roll over to the next period.
          - `max` number, nullable, required — Maximum rollover units. Null for unlimited rollover.
          - `max_percentage` number, nullable — Maximum rollover as a percentage (0-100) of included + prepaid grant. Mutually exclusive with max.
          - `expiry_duration_type` 'month' | 'forever', required — When rolled over units expire.
          - `expiry_duration_length` number — Number of periods before expiry.
      - `free_trial` object — Free trial configuration. If set, new customers can try this plan before being charged.
        - `duration_length` number, required — Number of duration_type periods the trial lasts.
        - `duration_type` 'day' | 'month' | 'year', required — Unit of time for the trial duration ('day', 'month', 'year').
        - `card_required` boolean, required — Whether a payment method is required to start the trial. If true, customer will be charged after trial ends.
        - `on_end` 'bill' | 'revert', nullable — Behavior when the trial ends. 'bill' charges the customer (default). 'revert' expires the trial and restores the customer's previous plan.
      - `created_at` number, required — Unix timestamp (ms) when the plan was created.
      - `env` 'sandbox' | 'live', required — Environment this plan belongs to ('sandbox' or 'live').
      - `archived` boolean, required — Whether the plan is archived. Archived plans cannot be attached to new customers.
      - `base_variant_id` string, nullable, required — Deprecated. Use variant_details.base_plan_id instead. If this is a variant, the ID of the base plan it was created from.
      - `variant_details` object — Details about how this variant relates to its latest base plan.
        - `base_plan_id` string, required — The ID of the base plan this variant was derived from.
        - `customize` object — The customization that transforms the base plan into this variant.
          - `price` object, nullable — Base price configuration for a plan.
            - `amount` number, required — Base price amount for the plan.
            - `interval` 'one_off' | 'week' | 'month' | 'quarter' | 'semi_annual' | 'year', required — Billing interval (e.g. 'month', 'year').
            - `interval_count` number — Number of intervals per billing cycle. Defaults to 1.
            - `additional_currencies` object[] — Base price amounts in additional currencies. The base 'amount' is in the org's default currency.
              - …
          - `add_items` object[] — Items to add to the plan.
            - `feature_id` string, required — The ID of the feature to configure.
            - `included` number — Number of free units included. Balance resets to this each interval for consumable features.
            - `unlimited` boolean — If true, customer has unlimited access to this feature.
            - `reset` object — Reset configuration for consumable features. Omit for non-consumable features like seats.
              - …
            - `price` object — Pricing for usage beyond included units. Omit for free features.
              - …
            - `proration` object — Proration settings for prepaid features. Controls mid-cycle quantity change billing.
              - …
            - `rollover` object — Rollover config for unused units. If set, unused included units carry over.
              - …
          - `remove_items` object[] — Filters selecting items to remove from the plan.
            - `feature_id` string — Match items linked to this feature.
            - `billing_method` 'prepaid' | 'usage_based' — Match items with this billing method (prepaid or usage_based).
            - `interval` union — Match items with this interval. Accepts either a BillingInterval (price-side) or a ResetInterval (reset-side, includes day/hour/minute) so price-less items keyed by reset.interval can be disambiguated.
              - …
            - `interval_count` integer — Match items with this interval_count. Disambiguates between items that share an interval but differ in count.
          - `free_trial` object, nullable — Free trial configuration for a plan.
            - `duration_length` number, required — Number of duration_type periods the trial lasts.
            - `duration_type` 'day' | 'month' | 'year' — Unit of time for the trial ('day', 'month', 'year').
            - `card_required` boolean — If true, payment method required to start trial. Customer is charged after trial ends.
            - `on_end` 'bill' | 'revert' — Behavior when the trial ends. 'bill' charges the customer (default). 'revert' expires the trial and restores the customer's previous plan.
          - `billing_controls` object — Override the plan's billing controls (auto top-ups, spend limits, usage limits, usage alerts, overage allowed) for this customer.
            - `auto_topups` object[] — List of auto top-up configurations per feature.
              - …
            - `spend_limits` object[] — List of overage spend limits per feature (caps overage spend).
              - …
            - `usage_limits` object[] — List of hard usage caps per feature (max units per interval).
              - …
            - `usage_alerts` object[] — List of usage alert configurations per feature.
              - …
            - `overage_allowed` object[] — List of overage allowed controls per feature. When enabled, usage can exceed balance.
              - …
      - `config` object, required — Miscellaneous plan-level configuration flags.
        - `ignore_past_due` boolean — If true, entitlements attached to this plan will still reset on schedule even when the customer's product is in a past_due state.
      - `billing_controls` object — Plan-level billing controls used as customer defaults.
        - `auto_topups` object[] — List of auto top-up configurations per feature.
          - `feature_id` string, required — The ID of the feature (credit balance) to auto top-up.
          - `enabled` boolean — Whether auto top-up is enabled.
          - `threshold` number, required — When the balance drops below this threshold, an auto top-up will be purchased.
          - `quantity` number, required — Amount of credits to add per auto top-up.
          - `purchase_limit` object — Optional rate limit to cap how often auto top-ups occur.
            - `interval` 'hour' | 'day' | 'week' | 'month', required — The time interval for the purchase limit window.
            - `interval_count` number — Number of intervals in the purchase limit window.
            - `limit` number, required — Maximum number of auto top-ups allowed within the interval.
          - `invoice_mode` boolean — When true, auto top-up creates a send_invoice invoice instead of auto-charging.
        - `spend_limits` object[] — List of overage spend limits per feature (caps overage spend).
          - `feature_id` string — Optional feature ID this spend limit applies to.
          - `enabled` boolean — Whether the overage spend limit is enabled.
          - `limit_type` 'absolute' | 'usage_percentage' — How overage_limit is interpreted: an absolute overage cap (default) or a percentage of the main-plan allowance.
          - `overage_limit` number — Overage cap for the feature: absolute units, or a percent (e.g. 120) when limit_type is usage_percentage.
          - `skip_overage_billing` boolean — When true, overage for this feature is not posted to Stripe. Usage tracking and balance resets still behave normally.
        - `usage_limits` object[] — List of hard usage caps per feature (max units per interval).
          - `feature_id` string, required — The feature this usage limit applies to.
          - `enabled` boolean — Whether this usage limit is enabled.
          - `limit` number, required — Maximum units allowed per interval.
          - `interval` 'day' | 'week' | 'month' | 'year', required — Interval for the cap, aligned to the customer's billing cycle.
          - `filter` object — When set, only usage from events whose properties match counts toward this cap. Omit to count all usage of the feature.
            - `properties` object, required
        - `usage_alerts` object[] — List of usage alert configurations per feature.
          - `feature_id` string — The feature ID this alert applies to.
          - `enabled` boolean — Whether this usage alert is enabled.
          - `threshold` number, required — The threshold value that triggers the alert. For usage or remaining, this is an absolute count. For usage_percentage or remaining_percentage, this is a percentage (0-100).
          - `threshold_type` 'usage' | 'usage_percentage' | 'remaining' | 'remaining_percentage', required — Whether the threshold is an absolute count or a percentage of the usage allowance or remaining balance.
          - `name` string — Optional user-defined label to distinguish multiple alerts on the same feature.
        - `overage_allowed` object[] — List of overage allowed controls per feature. When enabled, usage can exceed balance.
          - `feature_id` string, required — The feature ID this overage allowed control applies to.
          - `enabled` boolean — Whether overage is allowed for this feature.
      - `metadata` object, required — Arbitrary key-value metadata defined by you for your own use. Shared across all versions of the plan.
      - `customer_eligibility` object
        - `trial_available` boolean — Whether the trial on this plan is available to this customer. For example, if the customer used the trial in the past, this will be false.
        - `status` 'active' | 'scheduled' — The customer's current status with this plan. 'active' if attached, 'scheduled' if pending activation.
        - `canceling` boolean — Whether the customer's active instance of this plan is set to cancel.
        - `trialing` boolean — Whether the customer is currently on a free trial of this plan.
        - `attach_action` 'activate' | 'upgrade' | 'downgrade' | 'none' | 'purchase', required — The action that would occur if this plan were attached to the customer.
    - `feature_quantities` object[], required — The feature quantity selections associated with this plan change.
      - `feature_id` string, required — The ID of the adjustable feature included in this change.
      - `quantity` number, required — The quantity that will apply for this feature in the change.
    - `effective_at` number, nullable, required — When this change takes effect, in milliseconds since the Unix epoch, or null if it applies immediately.
    - `canceled_at` number, nullable, required — When this plan was canceled, in milliseconds since the Unix epoch, or null if it is not canceled.
    - `expires_at` number, nullable, required — When this plan expires, in milliseconds since the Unix epoch, or null if it does not expire.
  - `outgoing` object[], required — Products or subscription changes being removed or ended.
    - `plan_id` string, required — The ID of the plan affected by this preview change.
    - `plan` Plan
      - `id` string, required — Unique identifier for the plan.
      - `name` string, required — Display name of the plan.
      - `description` string, nullable, required — Optional description of the plan.
      - `group` string, nullable, required — Group identifier for organizing related plans. Plans in the same group are mutually exclusive.
      - `version` number, required — Version number of the plan. Incremented when plan configuration changes.
      - `add_on` boolean, required — Whether this is an add-on plan that can be attached alongside a main plan.
      - `auto_enable` boolean, required — If true, this plan is automatically attached when a customer is created. Used for free plans.
      - `price` object, nullable, required — Base recurring price for the plan. Null for free plans or usage-only plans.
        - `amount` number, required — Base price amount for the plan.
        - `additional_currencies` object[] — Base price amounts in additional currencies. The base 'amount' is in the org's default currency.
          - `currency` string, required — Three-letter Stripe-supported currency code (e.g. 'eur', 'gbp').
          - `amount` number, required — Price amount in this currency. Set explicitly per currency, not converted from the base amount.
        - `interval` 'one_off' | 'week' | 'month' | 'quarter' | 'semi_annual' | 'year', required — Billing interval (e.g. 'month', 'year').
        - `interval_count` number — Number of intervals per billing cycle. Defaults to 1.
        - `display` object — Display text for showing this price in pricing pages.
          - `primary_text` string, required — Main display text (e.g. '$10' or '100 messages').
          - `secondary_text` string — Secondary display text (e.g. 'per month' or 'then $0.5 per 100').
      - `items` object[], required — Feature configurations included in this plan. Each item defines included units, pricing, and reset behavior for a feature.
        - `feature_id` string, required — The ID of the feature this item configures.
        - `feature` object — The full feature object if expanded.
          - `id` string, required — The ID of the feature, used to refer to it in other API calls like /track or /check.
          - `name` string, nullable — The name of the feature.
          - `type` 'static' | 'boolean' | 'single_use' | 'continuous_use' | 'credit_system' | 'ai_credit_system', required — The type of the feature
          - `display` object, nullable — Singular and plural display names for the feature.
            - `singular` string, required — The singular display name for the feature.
            - `plural` string, required — The plural display name for the feature.
          - `credit_schema` object[], nullable — Credit cost schema for credit system features.
            - `metered_feature_id` string, required — The ID of the metered feature (should be a single_use feature).
            - `credit_cost` number, required — The credit cost of the metered feature.
          - `archived` boolean, nullable — Whether or not the feature is archived.
        - `included` number, required — Number of free units included. For consumable features, balance resets to this number each interval.
        - `unlimited` boolean, required — Whether the customer has unlimited access to this feature.
        - `reset` object, nullable, required — Reset configuration for consumable features. Null for non-consumable features like seats where usage persists across billing cycles.
          - `interval` 'one_off' | 'minute' | 'hour' | 'day' | 'week' | 'month' | 'quarter' | 'semi_annual' | 'year', required — The interval at which the feature balance resets (e.g. 'month', 'year'). For consumable features, usage resets to 0 and included units are restored.
          - `interval_count` number — Number of intervals between resets. Defaults to 1.
        - `price` object, nullable, required — Pricing configuration for usage beyond included units. Null if feature is entirely free.
          - `amount` number — Price per billing_units after included usage is consumed. Mutually exclusive with tiers.
          - `additional_currencies` object[] — Amounts in additional currencies for this flat price. The base 'amount' is in the org's default currency. Only valid with 'amount', not 'tiers' (tiered prices carry per-currency amounts on each tier).
            - `currency` string, required — Three-letter Stripe-supported currency code (e.g. 'eur', 'gbp').
            - `amount` number, required — Price amount in this currency. Set explicitly per currency, not converted from the base amount.
          - `tiers` object[] — Tiered pricing configuration. Each tier's 'to' INCLUDES the included amount. Either 'tiers' or 'amount' is required.
            - `to` union, required
              - …
            - `amount` number, required
            - `flat_amount` number
            - `additional_currencies` object[]
              - …
          - `tier_behavior` 'graduated' | 'volume'
          - `interval` 'one_off' | 'week' | 'month' | 'quarter' | 'semi_annual' | 'year', required — Billing interval for this price. For consumable features, should match reset.interval.
          - `interval_count` number — Number of intervals per billing cycle. Defaults to 1.
          - `billing_units` number, required — Number of units per price increment. Usage is rounded UP to the nearest billing_units when billed (e.g. billing_units=100 means 101 usage rounds to 200).
          - `billing_method` 'prepaid' | 'usage_based', required — 'prepaid' for features like seats where customers pay upfront, 'usage_based' for pay-as-you-go after included usage.
          - `max_purchase` number, nullable, required — Maximum units a customer can purchase beyond included. E.g. if included=100 and max_purchase=300, customer can use up to 400 total before usage is capped. Null for no limit.
        - `display` object — Display text for showing this item in pricing pages.
          - `primary_text` string, required — Main display text (e.g. '$10' or '100 messages').
          - `secondary_text` string — Secondary display text (e.g. 'per month' or 'then $0.5 per 100').
        - `rollover` object — Rollover configuration for unused units. If set, unused included units roll over to the next period.
          - `max` number, nullable, required — Maximum rollover units. Null for unlimited rollover.
          - `max_percentage` number, nullable — Maximum rollover as a percentage (0-100) of included + prepaid grant. Mutually exclusive with max.
          - `expiry_duration_type` 'month' | 'forever', required — When rolled over units expire.
          - `expiry_duration_length` number — Number of periods before expiry.
      - `free_trial` object — Free trial configuration. If set, new customers can try this plan before being charged.
        - `duration_length` number, required — Number of duration_type periods the trial lasts.
        - `duration_type` 'day' | 'month' | 'year', required — Unit of time for the trial duration ('day', 'month', 'year').
        - `card_required` boolean, required — Whether a payment method is required to start the trial. If true, customer will be charged after trial ends.
        - `on_end` 'bill' | 'revert', nullable — Behavior when the trial ends. 'bill' charges the customer (default). 'revert' expires the trial and restores the customer's previous plan.
      - `created_at` number, required — Unix timestamp (ms) when the plan was created.
      - `env` 'sandbox' | 'live', required — Environment this plan belongs to ('sandbox' or 'live').
      - `archived` boolean, required — Whether the plan is archived. Archived plans cannot be attached to new customers.
      - `base_variant_id` string, nullable, required — Deprecated. Use variant_details.base_plan_id instead. If this is a variant, the ID of the base plan it was created from.
      - `variant_details` object — Details about how this variant relates to its latest base plan.
        - `base_plan_id` string, required — The ID of the base plan this variant was derived from.
        - `customize` object — The customization that transforms the base plan into this variant.
          - `price` object, nullable — Base price configuration for a plan.
            - `amount` number, required — Base price amount for the plan.
            - `interval` 'one_off' | 'week' | 'month' | 'quarter' | 'semi_annual' | 'year', required — Billing interval (e.g. 'month', 'year').
            - `interval_count` number — Number of intervals per billing cycle. Defaults to 1.
            - `additional_currencies` object[] — Base price amounts in additional currencies. The base 'amount' is in the org's default currency.
              - …
          - `add_items` object[] — Items to add to the plan.
            - `feature_id` string, required — The ID of the feature to configure.
            - `included` number — Number of free units included. Balance resets to this each interval for consumable features.
            - `unlimited` boolean — If true, customer has unlimited access to this feature.
            - `reset` object — Reset configuration for consumable features. Omit for non-consumable features like seats.
              - …
            - `price` object — Pricing for usage beyond included units. Omit for free features.
              - …
            - `proration` object — Proration settings for prepaid features. Controls mid-cycle quantity change billing.
              - …
            - `rollover` object — Rollover config for unused units. If set, unused included units carry over.
              - …
          - `remove_items` object[] — Filters selecting items to remove from the plan.
            - `feature_id` string — Match items linked to this feature.
            - `billing_method` 'prepaid' | 'usage_based' — Match items with this billing method (prepaid or usage_based).
            - `interval` union — Match items with this interval. Accepts either a BillingInterval (price-side) or a ResetInterval (reset-side, includes day/hour/minute) so price-less items keyed by reset.interval can be disambiguated.
              - …
            - `interval_count` integer — Match items with this interval_count. Disambiguates between items that share an interval but differ in count.
          - `free_trial` object, nullable — Free trial configuration for a plan.
            - `duration_length` number, required — Number of duration_type periods the trial lasts.
            - `duration_type` 'day' | 'month' | 'year' — Unit of time for the trial ('day', 'month', 'year').
            - `card_required` boolean — If true, payment method required to start trial. Customer is charged after trial ends.
            - `on_end` 'bill' | 'revert' — Behavior when the trial ends. 'bill' charges the customer (default). 'revert' expires the trial and restores the customer's previous plan.
          - `billing_controls` object — Override the plan's billing controls (auto top-ups, spend limits, usage limits, usage alerts, overage allowed) for this customer.
            - `auto_topups` object[] — List of auto top-up configurations per feature.
              - …
            - `spend_limits` object[] — List of overage spend limits per feature (caps overage spend).
              - …
            - `usage_limits` object[] — List of hard usage caps per feature (max units per interval).
              - …
            - `usage_alerts` object[] — List of usage alert configurations per feature.
              - …
            - `overage_allowed` object[] — List of overage allowed controls per feature. When enabled, usage can exceed balance.
              - …
      - `config` object, required — Miscellaneous plan-level configuration flags.
        - `ignore_past_due` boolean — If true, entitlements attached to this plan will still reset on schedule even when the customer's product is in a past_due state.
      - `billing_controls` object — Plan-level billing controls used as customer defaults.
        - `auto_topups` object[] — List of auto top-up configurations per feature.
          - `feature_id` string, required — The ID of the feature (credit balance) to auto top-up.
          - `enabled` boolean — Whether auto top-up is enabled.
          - `threshold` number, required — When the balance drops below this threshold, an auto top-up will be purchased.
          - `quantity` number, required — Amount of credits to add per auto top-up.
          - `purchase_limit` object — Optional rate limit to cap how often auto top-ups occur.
            - `interval` 'hour' | 'day' | 'week' | 'month', required — The time interval for the purchase limit window.
            - `interval_count` number — Number of intervals in the purchase limit window.
            - `limit` number, required — Maximum number of auto top-ups allowed within the interval.
          - `invoice_mode` boolean — When true, auto top-up creates a send_invoice invoice instead of auto-charging.
        - `spend_limits` object[] — List of overage spend limits per feature (caps overage spend).
          - `feature_id` string — Optional feature ID this spend limit applies to.
          - `enabled` boolean — Whether the overage spend limit is enabled.
          - `limit_type` 'absolute' | 'usage_percentage' — How overage_limit is interpreted: an absolute overage cap (default) or a percentage of the main-plan allowance.
          - `overage_limit` number — Overage cap for the feature: absolute units, or a percent (e.g. 120) when limit_type is usage_percentage.
          - `skip_overage_billing` boolean — When true, overage for this feature is not posted to Stripe. Usage tracking and balance resets still behave normally.
        - `usage_limits` object[] — List of hard usage caps per feature (max units per interval).
          - `feature_id` string, required — The feature this usage limit applies to.
          - `enabled` boolean — Whether this usage limit is enabled.
          - `limit` number, required — Maximum units allowed per interval.
          - `interval` 'day' | 'week' | 'month' | 'year', required — Interval for the cap, aligned to the customer's billing cycle.
          - `filter` object — When set, only usage from events whose properties match counts toward this cap. Omit to count all usage of the feature.
            - `properties` object, required
        - `usage_alerts` object[] — List of usage alert configurations per feature.
          - `feature_id` string — The feature ID this alert applies to.
          - `enabled` boolean — Whether this usage alert is enabled.
          - `threshold` number, required — The threshold value that triggers the alert. For usage or remaining, this is an absolute count. For usage_percentage or remaining_percentage, this is a percentage (0-100).
          - `threshold_type` 'usage' | 'usage_percentage' | 'remaining' | 'remaining_percentage', required — Whether the threshold is an absolute count or a percentage of the usage allowance or remaining balance.
          - `name` string — Optional user-defined label to distinguish multiple alerts on the same feature.
        - `overage_allowed` object[] — List of overage allowed controls per feature. When enabled, usage can exceed balance.
          - `feature_id` string, required — The feature ID this overage allowed control applies to.
          - `enabled` boolean — Whether overage is allowed for this feature.
      - `metadata` object, required — Arbitrary key-value metadata defined by you for your own use. Shared across all versions of the plan.
      - `customer_eligibility` object
        - `trial_available` boolean — Whether the trial on this plan is available to this customer. For example, if the customer used the trial in the past, this will be false.
        - `status` 'active' | 'scheduled' — The customer's current status with this plan. 'active' if attached, 'scheduled' if pending activation.
        - `canceling` boolean — Whether the customer's active instance of this plan is set to cancel.
        - `trialing` boolean — Whether the customer is currently on a free trial of this plan.
        - `attach_action` 'activate' | 'upgrade' | 'downgrade' | 'none' | 'purchase', required — The action that would occur if this plan were attached to the customer.
    - `feature_quantities` object[], required — The feature quantity selections associated with this plan change.
      - `feature_id` string, required — The ID of the adjustable feature included in this change.
      - `quantity` number, required — The quantity that will apply for this feature in the change.
    - `effective_at` number, nullable, required — When this change takes effect, in milliseconds since the Unix epoch, or null if it applies immediately.
    - `canceled_at` number, nullable, required — When this plan was canceled, in milliseconds since the Unix epoch, or null if it is not canceled.
    - `expires_at` number, nullable, required — When this plan expires, in milliseconds since the Unix epoch, or null if it does not expire.
  - `intent` 'update_plan' | 'update_quantity' | 'cancel_immediately' | 'cancel_end_of_cycle' | 'uncancel' | 'none', required
  - `tax` object — Tax preview for the immediate charge. Contact us to enable the tax flag on your organisation. Shows only with flag enabled, a Stripe customer exists and has a location.
    - `total` number, required — Total tax amount in major currency units.
    - `amount_inclusive` number, required — Tax included in line item subtotals.
    - `amount_exclusive` number, required — Tax added on top of subtotals.
    - `currency` string, required — Three-letter currency code.
    - `status` 'complete' | 'incomplete', required — Calculation status ('complete' when Stripe Tax succeeds or 'incomplete' when Stripe Tax returned 0 or errored).
  - `invoice_credits` object — Stripe customer invoice credits preview.
    - `balance` number, required — Stripe customer credit balance available, expressed as a positive number in major currency units.
    - `currency` string, required — Three-letter currency code.

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[API](https://skmtc.net/useautumn/apis/autumn-api.md) · [All operations](https://skmtc.net/useautumn/apis/autumn-api/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/useautumn/autumn-api/revisions/29536933c0dc/schema)