---
title: "Create a Counterparty"
method: POST
path: "/counterparties"
tags: ["Counterparty"]
---

# Create a Counterparty

`POST /counterparties`

Create a Counterparty.

## Headers

- `Idempotency-Key` string, required

## Request body

- CounterpartyCreateRequest
  - `customerId` string, required — Owning customer (cst_… TypeID or legacy public id).
  - `name` string, required — Full legal name or registered business name. 1..140 chars.
  - `entityType` 'individual' | 'business'
  - `address` Address, required — A postal address. country is an ISO 3166-1 alpha-2 country code.
    - `line1` string — Street address, line 1.
    - `line2` string — Street address, line 2.
    - `city` string — City.
    - `state` string — State / province / region.
    - `country` string — ISO 3166-1 alpha-2
    - `zipCode` string — ZIP / postal code.
  - `email` string — Contact email address.
  - `phone` string — Phone in E.164 format.
  - `taxId` string — Tax ID (CPF, CNPJ, SSN, etc.). Required for some external-account types.
  - `dateOfBirth` string, date — Date of birth (YYYY-MM-DD).
  - `nationality` string — ISO 3166-1 alpha-2.
  - `metadata` object — Free-form key-value pairs stored on the resource and echoed back on reads.

## Response `201`

The request has succeeded and a new resource has been created as a result.

- Counterparty — A third party a customer transacts with - an entry in the customer's address book. Counterparties will own External Accounts (registered payment destinations) in a later slice.
  - `id` string — Public TypeID, e.g. `txn_01h455vb4pex5vsknk084sn02q`; legacy UUID suffixes are accepted until non-v7 rows are retired.
  - `object` 'counterparty'
  - `customerId` string — Public TypeID, e.g. `txn_01h455vb4pex5vsknk084sn02q`; legacy UUID suffixes are accepted until non-v7 rows are retired.
  - `status` 'active' | 'rejected' | 'deleted' — Lifecycle of a counterparty. `rejected` is reserved for create-time compliance screening (not yet active); `deleted` marks a soft-deleted record that remains readable by id.
  - `rejectionReason` string — Set when status = `rejected`.
  - `name` string — Full legal name or registered business name.
  - `entityType` 'individual' | 'business'
  - `address` Address, required — A postal address. country is an ISO 3166-1 alpha-2 country code.
    - `line1` string — Street address, line 1.
    - `line2` string — Street address, line 2.
    - `city` string — City.
    - `state` string — State / province / region.
    - `country` string — ISO 3166-1 alpha-2
    - `zipCode` string — ZIP / postal code.
  - `email` string
  - `phone` string
  - `taxId` string
  - `dateOfBirth` string, date
  - `nationality` string — ISO 3166-1 alpha-2.
  - `metadata` object
  - `createdAt` string, date-time
  - `updatedAt` string, date-time

---

[API](https://skmtc.net/polygon-technology/apis/polygon-oms-public-api.md) · [All operations](https://skmtc.net/polygon-technology/apis/polygon-oms-public-api/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/polygon-technology/polygon-oms-public-api/revisions/18fdaebf64e5/schema)