# Update Debit Memo

`PATCH /accounting/debit-memos/{id}`

Group: Accounting › Debit Memos · Operation ID: `updateDebitMemo`

Updates the customer message, purchase-order reference or payment term of the debit memo. Only the fields in the request body change. Changing the payment term does not recompute the due date. Use the debit memo's id, not its debitMemoNumber.

Everything omitted from the request body is left as it was. Only customerMessage, purchaseOrder and paymentTerm can change. A debit memo is approved on create and has already posted its journal entry, so nothing that would move the posting or the aging can change: not the dates, amounts, lines, GL account or addresses. Changing paymentTerm does not recompute dueDate. The response is empty. Read the updated record with GET accounting/debit-memos/:id.

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

## 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. |
| `id` | path | string | yes | The unique identifier for the debit memo to update. |

## Request body

Required, `application/json`: updateDebitMemoInput.

| Field | Type | Required | Description |
| --- | --- | --- | --- |
| `customerMessage` | string | no | A new free-text message to show the customer on the document. Pass an empty string to clear it. |
| `purchaseOrder` | string | no | A new purchase-order reference from the customer. Pass an empty string to clear it. |
| `paymentTerm` | string | no | A new payment-term key to record on the document. This does not recompute dueDate. See code on GET accounting/payment-terms. |

Example:

```json
{
  "customerMessage": "Revised: covers the re-debited licence fee only.",
  "purchaseOrder": "PO-88214",
  "paymentTerm": "<paymentTerm>"
}
```

## Response

`200` Success

## 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 |
| --- | --- |
| `NOT_FOUND` | 400 |
| `IDEMPOTENCY_KEY_CONFLICT` | 409 |
| `IDEMPOTENCY_PAYLOAD_MISMATCH` | 422 |

## Statuses

- `400` — Invalid request or business failure. Codes: NOT_FOUND
- `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