# invoices.send

Send an invoice to the customer's billing contacts from the invoices sender identity with the PDF attached, issuing it first if needed. The email is queued and the invoice marked sent together, and an invoice's first email goes out only once; sending an already-sent invoice again is a deliberate resend. Use method manual to record that you delivered it yourself.

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

Permissions: `accounting:read`, `accounting:write` · Roles: admin, finance · Idempotency key required · Send `expectedRevision` · Reaches outside Oatmilk (email or a provider)

MCP tool: `accounting_invoices_send`

## Fields

| Field | Type | Required | Notes |
| --- | --- | --- | --- |
| `id` | string (ID) | Yes | The record's ID. |
| `expectedRevision` | integer | Yes | The record's current revision, from the last time you read it. If someone changed the record since, the request is refused with a conflict so you can reload and check before trying again. at most 9007199254740991; greater than 0. |
| `method` | enum |  | One of: `email`, `manual`. Default `"email"`. |
| `issueDate` | string |  | The date the document was issued, as YYYY-MM-DD. |
| `to` | array of strings (email) |  | The last date to include, as YYYY-MM-DD. 1–10 items; each at most 320 characters. |
| `cc` | array of strings (email) |  | at most 10 items; each at most 320 characters. |
| `message` | string |  | at most 2000 characters. |
| `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.send \
  -H "Authorization: Bearer $OATMILK_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $(uuidgen)" \
  -d '{
  "id": "9a8b7c6d-5e4f-4a3b-8c2d-1e0f9a8b7c6d",
  "expectedRevision": 3
}'
```

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