# contractors.payments.link

Link an outgoing bank transaction to a contractor, with its expected revision, treatment, reason and idempotency key. Remembering its payee can identify later payments; no payout is sent.

`POST /api/v1/accounting/contractors.payments.link`

Permissions: `accounting:read`, `accounting:write` · Roles: admin, finance · Idempotency key required

MCP tool: `accounting_contractors_payments_link`

## Fields

| Field | Type | Required | Notes |
| --- | --- | --- | --- |
| `contractorId` | string (ID) | Yes | The ID of a contractor, from contractors.list. |
| `transactionId` | string (ID) | Yes | The ID of a bank or card transaction, from transactions.list. |
| `expectedTransactionRevision` | integer | Yes | The bank transaction's current revision, from the last time you read it. at most 9007199254740991; greater than 0. |
| `treatment` | enum |  | One of: `services`, `reimbursement`, `unknown`. Default `"unknown"`. |
| `reason` | string | Yes | A short note saying why, kept in the record's history. 3–1000 characters. |
| `remember` | boolean |  | Default `true`. |
| `respectPersonDecision` | boolean |  | Default `false`. |
| `idempotencyKey` | string | Yes | Any unique text you generate once per intended change, so a retried request only happens once. Send it as the Idempotency-Key header instead if you prefer; if you send both they must match. 8–150 characters. |

## Example request

```bash
curl https://app.getoatmilk.com/api/v1/accounting/contractors.payments.link \
  -H "Authorization: Bearer $OATMILK_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $(uuidgen)" \
  -d '{
  "contractorId": "4d5e6f7a-8b9c-4d0e-8f1a-2b3c4d5e6f7a",
  "transactionId": "7f0f6c1e-1c1f-4b5e-9c8d-2f5e8e3c1a10",
  "expectedTransactionRevision": 3,
  "reason": "Synthetic example from the docs"
}'
```

Reference page: https://app.getoatmilk.com/docs/api/contractors.payments.link