# Source of funds, purpose, and documents

Supply source of funds, payment purpose, recipient reference, and payment evidence.

Product: Payment API
Guides follow API reference 0.1.0 and event reference 0.1.0.
Canonical page: https://docs.axiym.io/payment-api/integration-guide/prepare-payout-data/payment-fields

These fields describe the origin of the funds, the reason for the payment, and
its supporting evidence in Axiym's payout input. To use your own field names or
labels, see [Payment Data Maps](/payment-api/integration-guide/prepare-payout-data/payment-data-maps).

| Field                   | Type or format             | Requiredness | Description                                                                                                                                                                                             |
| ----------------------- | -------------------------- | ------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `sourceOfFunds`         | SourceOfFunds              | Conditional  | Origin of the funds used for this payment. Required where the corridor requires a source-of-funds code, including when `sender` is omitted. Use an Axiym code, or a saved label on the mapped endpoint. |
| `purpose`               | TransactionPurpose         | Conditional  | Business purpose of the payout. Use an Axiym code, or a saved label on the mapped endpoint. Required where the corridor requires a purpose code.                                                        |
| `reference`             | String                     | Recommended  | Text shown to the recipient, typically the invoice number.                                                                                                                                              |
| `supportingDocuments[]` | SupportingDocumentInput\[] | Conditional  | Documents supporting the payment, such as an invoice. Required where the corridor requires evidence.                                                                                                    |

`sourceOfFunds` describes where the money came from, such as business income or
a loan. `purpose` describes what the payment is for.

Direct requests require exact Axiym codes. On the mapped endpoint, any other
label must have an exact translation in the saved Payment Data Map.

Evidence about the parties does not belong here. Documents that describe the
sender or recipient go in `sender.documents[]` or `recipient.documents[]`, and
documents that evidence an identification (a registry extract, a passport scan)
go in the corresponding `identification.documents[]`. See
[Supporting documents](/payment-api/integration-guide/prepare-payout-data/supporting-documents).

## Example

Replace the document placeholder with the base64 encoding of a complete sandbox
fixture. See [Supporting documents](/payment-api/integration-guide/prepare-payout-data/supporting-documents)
for encoding instructions; the placeholder is not valid document content.

```json
{
  "sourceOfFunds": "BUSINESS_INCOME",
  "purpose": "GOODS_PURCHASE",
  "reference": "INV-2026-0917",
  "supportingDocuments": [
    {
      "documentType": "INVOICE",
      "name": "INV-2026-0917.pdf",
      "data": "REPLACE_WITH_BASE64_ENCODED_INVOICE"
    }
  ]
}
```

See [Controlled values](/payment-api/integration-guide/prepare-payout-data/controlled-values)
for the canonical vocabularies and [Value mapping](/payment-api/integration-guide/prepare-payout-data/payment-data-maps#value-mapping)
for using your own labels with a saved map.