pacs.008
The ISO 20022 message that carries a customer payment from bank to bank, and the one that took over MT103's job.
Its full name is FIToFICustomerCreditTransfer. It is XML with a group header and one or more transaction blocks, where each payment carries an EndToEndId set by the payer and, on the Swift network, a UETR that follows it through the entire chain. Addresses and parties have their own structured fields, so a sanctions screen no longer has to guess which bit is the street and which is the city. Its siblings pacs.002 report status and pacs.004 send the money back.
SEPA credit transfers have used variants of it from the start, TARGET2 switched in March 2023 and Swift's cross-border traffic in November 2025. During the migration, pacs.008 was often converted to MT103 somewhere along the way, truncating the rich data to 35-character lines. The benefit only shows up once every bank in the chain speaks the format.