# Reverse Journal Entry

`POST /accounting/journal-entries/{id}/reverse`

Group: Accounting › Journal Entries · Operation ID: `reverseJournalEntry`

Reverses a posted journal entry by posting a new entry with its debits and credits swapped. Fails when the entry cannot be reversed, such as one that is not manual, is already reversed, is itself a reversal, or was generated by revaluation. Returns the new reversal entry's id.

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

## 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 journal entry to reverse. |

## Request body

Required, `application/json`: reverseJournalEntryInput.

| Field | Type | Required | Description |
| --- | --- | --- | --- |
| `reversalDate` | string (date) | yes | The posting date of the reversal entry. Use format YYYY-MM-DD. It must be on or after the original entry's posting date. |
| `reversalReason` | string | yes | The reason for the reversal. Accepted values: 'accrualReversal', 'revaluationReversal', 'estimate', 'rebook', 'reversingSFD', 'other'. |
| `reversalDescription` | string | no | A free-form reversal description recorded on the original entry's header. Required unless reversalReason is 'other', which fails with REVERSAL_DESCRIPTION_REQUIRED. |

Example:

```json
{
  "reversalDate": "2026-01-15",
  "reversalReason": "<reversalReason>",
  "reversalDescription": "<reversalDescription>"
}
```

## Response

`200` Success

Under `data` (reverseJournalEntryOutput):

| Field | Type | Required | Description |
| --- | --- | --- | --- |
| `reversalJournalEntryId` | string | yes | The unique identifier for the created reversal journal entry. |

## 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 |
| `REVERSAL_DESCRIPTION_REQUIRED` | 400 |
| `IDEMPOTENCY_KEY_CONFLICT` | 409 |
| `IDEMPOTENCY_PAYLOAD_MISMATCH` | 422 |

## Statuses

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