# Book draft invoice

`POST /v1/invoices/{id}/book`

Books a draft invoice to the ledger and assigns its number. Each call is your own approval of the invoice: Numina does not review it, so make sure a person at your company has checked it or has approved the rules your system books by. Booking is final and cannot be undone through this API. It does not send the invoice; use POST /v1/invoices/{id}/send.

Not available to Fuld Service customers (403 `booking_not_available`), whose books Numina's bookkeepers keep.

Returns 400 `validation_error` for a date in a closed accounting year or before the first accounting date, VAT on a company that is not VAT registered, an e-invoice that cannot be sent, or an invoice that is not complete. Returns 400 `payment_details_required` for an invoice with no payment details when the company has no default bank account to fill them from (see `is_invoice_default` on GET /v1/bank-accounts); create the invoice again with `bank_account_id`. A foreign-currency invoice uses the latest exchange rate Numina has on or before its issue date; see `currency_rate` on POST /v1/invoices.

Safe to retry: booking an invoice that is already booked returns it unchanged with 200. Credit notes and offers cannot be booked here and return 409.

**Scopes:** any of `invoices:book`, `write:ledger`

## Request

```bash
curl -X POST https://api.numina.app/v1/invoices/550e8400-e29b-41d4-a716-446655440000/book \
  -H "Authorization: Bearer numi_YOUR_API_KEY"
```

## Path parameters

- `id` (string (uuid), required): Invoice ID

## Response `200`

The booked invoice

```json
{
  "id": "550e8400-e29b-41d4-a716-446655440000",
  "invoice_number": 1001,
  "type": "invoice",
  "credited_invoice_id": "550e8400-e29b-41d4-a716-446655440000",
  "status": "sent",
  "issue_date": "2026-01-15",
  "due_date": "2026-02-15",
  "contact_id": "550e8400-e29b-41d4-a716-446655440001",
  "contact_name": "Acme ApS",
  "currency": "DKK",
  "subtotal": 10000,
  "vat": 2500,
  "vat_rate": 25,
  "total": 12500,
  "has_mixed_vat": false,
  "outstanding_balance": 12500,
  "outstanding_balance_currency": "DKK",
  "currency_rate": 0,
  "delivery_status": "sent",
  "email_delivery_status": "string",
  "email_sent_at": "string",
  "e_invoice_sent_at": "string",
  "is_overdue": false,
  "payment_state": "open",
  "unmatched_payments_note": "string",
  "items": [
    {
      "unit": "string",
      "vat_account_id": "string",
      "vat_code": "string",
      "sales_account_number": 0,
      "vat_rate": 0,
      "id": "550e8400-e29b-41d4-a716-446655440002",
      "description": "Consulting services",
      "quantity": 10,
      "unit_price": 1000
    }
  ],
  "memo": "Project Q1 delivery",
  "payment_details": {
    "bank_name": "Danske Bank",
    "scheme": "dk-registration-number",
    "clearing_code": "3409",
    "account_number": "0012345678",
    "iban": "DK5030000012345678",
    "swift_bic": "DABADKKK"
  },
  "created_at": "2026-01-15T10:30:00Z"
}
```

## Errors

- `400` Bad Request - Invalid input or validation failed
- `401` Unauthorized - Invalid or missing authentication
- `403` Forbidden - Missing scope, the company is archived, or the company is on Fuld Service
- `404` Not Found - The resource does not exist in this company
- `409` Conflict - This is a credit note or offer, or the invoice is being updated
- `429` Too Many Requests - Rate limit exceeded
- `500` Internal Server Error

See https://developers.numina.app/errors.md for the error format.