pacs.002
The ISO 20022 message in which one bank tells another what became of a payment: accepted, pending or rejected.
Its full name is FIToFIPaymentStatusReport. It points back at an earlier payment, usually a pacs.008, and gives a status as a four-letter code: ACCP for accepted, ACSC for settled, PDNG for pending and RJCT for rejected. A rejection carries a reason code from the ISO 20022 external code lists, such as AC01 for an incorrect account number or AM04 for insufficient funds.
A rejection happens before the money has settled, which is what separates it from a return. In instant schemes such as SCT Inst, the pacs.002 is the entire answer to whether the payment went through, and it has to arrive within seconds. In older flows a rejection could turn up days later as free text in an MT message, waiting for a human to read it.