v1
latestOpenAPI 3.1.02026-07-265817860.8 KBbilling
Previews the billing changes that would occur when attaching multiple plans, without actually making any changes.
Use this endpoint to show customers what they will be charged before confirming a multi-plan subscription.
post/v1/billing.preview_multi_attach
Headers
x-api-versionstring required
Request body
Example request
{
"customer_id": "cus_123",
"plans": [
{
"plan_id": "pro_plan"
},
{
"plan_id": "addon_seats",
"feature_quantities": [
{
"feature_id": "seats",
"quantity": 5
}
]
}
]
}Response
OK
Example response
{
"customerId": "charles",
"lineItems": [
{
"display_name": "Pro seed",
"description": "Pro seed - Base Price (from 18 Feb 2026 to 18 Mar 2026)",
"subtotal": 20,
"total": 20,
"discounts": []
}
],
"subtotal": 20,
"total": 20,
"currency": "usd"
}