# Creates a refund against a source payment.

`POST /accounting/refunds`

Group: Accounting › Refunds · Operation ID: `createRefund`

Creates a refund against a source payment. When the payment lacks enough unapplied balance, list invoices in unapply to free balance first, in the same request. The refund is created approved, which triggers the external payment-provider sync, so there is no separate approval step over this API. customerId, entityId and currency are not inputs. They are derived from the source payment, so a refund cannot disagree with the payment it is against.

[Open in the interactive reference](https://docs.api.lensing.ai/?op=createRefund)

## Parameters

| Name | In | Type | Required | Description |
| --- | --- | --- | --- | --- |
| `Api-Version` | header | `"v1"` | yes | The API version this request targets, named by its public identifier. Required on every request; omitting it, or naming a version this company does not have, is answered with 400. This document describes version `v1`. |
| `Idempotency-Key` | header | string | no | An opaque caller-chosen string (1-255 characters) that makes this request safe to retry. Repeating the same key with an identical request body replays the original response instead of re-executing - but only once that original request succeeded; a failed attempt re-executes on retry. Repeating the key with a different body is answered with 422. A key still in flight is answered with 409 - as is a key whose original request was interrupted before it finished, for a few minutes afterwards, until that attempt is presumed dead. A completed response stays replayable for 24 hours. The key is scoped to the caller, not to the action: reusing it for a different action is answered with 409 or 422 rather than treated independently. On read actions this header is ignored. On write actions that cannot offer the guarantee it is answered with `400 IDEMPOTENCY_NOT_SUPPORTED` rather than silently ignored. |

## Request body

Required, `application/json`: createRefundInput.

| Field | Type | Required | Description |
| --- | --- | --- | --- |
| `paymentId` | string | yes | The source payment being refunded. See id on GET accounting/payments/:id. |
| `refundDate` | string (date) | yes | The date the refund is issued. Use format YYYY-MM-DD. Must fall in an open accounting period. |
| `refundType` | string, one of `"check"`, `"ach"`, `"wire"`, `"creditCard"`, `"directDebit"`, `"sepaCreditTransfer"` | yes | The payment method used for the refund. |
| `amount` | string (decimal) | yes | The refund amount, in the source payment's currency. Must be greater than 0. |
| `refundNote` | string | no | A free-form note attached to the refund. |
| `unapply` | array of object | no | Invoices to unapply the source payment from before the refund is created, freeing balance for the refund. The amount unapplied from each invoice is recognized on refundDate. |
| `unapply[].invoiceId` | string | yes | The invoice to unapply the payment from. See id on GET accounting/invoices/:id. |
| `unapply[].amount` | string (decimal) | yes | The amount to unapply from this invoice, in the payment currency. |

Example:

```json
{
  "paymentId": "5a0f3e6d-81b7-4c8e-9b21-9c2a6a107d34",
  "refundDate": "2026-08-01",
  "refundType": "ach",
  "amount": "150.00",
  "refundNote": "Customer requested partial refund",
  "unapply": [
    {
      "invoiceId": "3fa85f64-5717-4562-b3fc-2c963f66afa6",
      "amount": "19.99"
    }
  ]
}
```

## Response

`200` Success

Under `data` (createRefundOutput):

| Field | Type | Required | Description |
| --- | --- | --- | --- |
| `id` | string | yes | The unique identifier for the created refund. |
| `refundNumber` | string | no | The refund number, unique within the tenant, for example 'REF-1042'. Assigned on create. |
| `refundDate` | string (date) | yes | The date the refund was issued. Format YYYY-MM-DD. |
| `approvalStatus` | string | no | The approval status, always 'approved' immediately after create. |
| `refundType` | string | yes | The payment method used for the refund. Possible values: 'check', 'ach', 'wire', 'creditCard', 'directDebit', 'sepaCreditTransfer'. |
| `currency` | string | yes | The currency of the refund, derived from the source payment. Every amount on it is in this currency. Format ISO 4217, for example 'USD'. |
| `amount` | string (decimal) | yes | The refund amount, in the refund currency. |
| `customerId` | string | yes | The customer receiving the refund, derived from the source payment. See id on GET accounting/customers/:id. |
| `entityId` | string | yes | The legal entity issuing the refund, derived from the source payment. See id on GET base/entities. |
| `paymentId` | string | yes | The source payment being refunded. See id on GET accounting/payments/:id. |
| `lastModifiedDate` | string (date-time) | yes | The date and time the refund last changed, in UTC. Format YYYY-MM-DDTHH:mm:ss.sssZ. |

## Response headers

- `Idempotency-Replayed` — Present and `true` only when this response replays a previously stored one for the same Idempotency-Key, rather than reflecting a live execution. Absent on a live response - never sent as `false`.

## Errors

| Code | Status |
| --- | --- |
| `PAYMENT_NOT_FOUND` | 400 |
| `INVOICE_NOT_FOUND` | 400 |
| `INVALID_AMOUNT` | 400 |
| `IDEMPOTENCY_KEY_CONFLICT` | 409 |
| `IDEMPOTENCY_PAYLOAD_MISMATCH` | 422 |

## Statuses

- `400` — Invalid request or business failure. Codes: PAYMENT_NOT_FOUND, INVOICE_NOT_FOUND, INVALID_AMOUNT
- `401` — Missing or invalid access token
- `403` — Not authorized
- `404` — Not found
- `409` — The Idempotency-Key is still being processed by another request.
- `422` — The Idempotency-Key was already used with a different request payload.
- `429` — Too many requests
- `500` — Internal server error