# RefundInvoiceInput

A model the API reference uses in a request or a response. The operation pages link every field typed as this model here.

Input for the operator-facing refund of an invoice's collected payments.

## Fields
- `reason` (string): Operator-supplied reason for the refund. Recorded on the refund entry and on the invoice's  activity timeline, and threaded onto the gateway operation's audit note. (nullable, max length 500)
- `idempotencyKey` (string): Optional caller-supplied idempotency key. When omitted, the service derives a deterministic  key per refunded payment so a retry after a timeout replays the original outcome rather than  returning the money twice. Conditional: When IdempotencyKey is not empty. Pattern: ^[A-Za-z0-9._:-]+$. (nullable, max length 128)

## See also

- [All documentation](https://devportal.demo.winkpg.io/llms.txt): the machine-readable index of every public page on this site.