Initiate a refund of a payment back to the buyer. Refunds are always for the full payment amount. Partial refunds are not supported.

The same eligibility rules as the Finexio self-service portal apply: the payment must not be complete, must have no correction already in progress, and must not be flagged for fraud review. Check payments are eligible; card payments are eligible only while the card is unused (no purchase or authorization has occurred and the card still holds its full balance). ACH, wire, and international payments are not eligible for self-service correction — contact Finexio support to correct these.

This endpoint is safe to retry. If a correction is already in progress for the payment — whether created by an earlier API call, the Finexio portal, or Finexio operations — no second correction is created and no error is returned; instead the response is 200 OK with already_in_progress: true and the existing correction's current state.