# invoices.duplicate

Create a new draft from an existing invoice, or from a customer's last invoice when partyId is given. The new draft keeps the source invoice's project.

`POST /api/v1/accounting/invoices.duplicate`

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

MCP tool: `accounting_invoices_duplicate`

## Fields

| Field | Type | Required | Notes |
| --- | --- | --- | --- |
| `id` | string (ID) |  | The record's ID. |
| `partyId` | string (ID) |  | The ID of a customer or vendor account, from parties.list. |
| `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. 8–200 characters. |

## Example request

```bash
curl https://app.getoatmilk.com/api/v1/accounting/invoices.duplicate \
  -H "Authorization: Bearer $OATMILK_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $(uuidgen)" \
  -d '{
  "id": "9a8b7c6d-5e4f-4a3b-8c2d-1e0f9a8b7c6d"
}'
```

Reference page: https://app.getoatmilk.com/docs/api/invoices.duplicate