The Technical Layer: Every Message Is Addressed to the System Itself

Every message sent to T2 is addressed to the system itself in the Business Application Header, known as the BAH. The BAH is the head.001 message that wraps every ISO 20022 payment, and it carries a From field and a To field. The From field names the BIC of the bank or branch that sends the message, and the To field names the BIC of the T2 service itself. A pacs.008 from Deutsche Bank to BNP Paribas carries From DEUTDEFFXXX and To as the T2 RTGS service, not To BNPAFRPPXXX. The receiving bank is named inside the pacs.008, not in the header that carries it. The rule exists because T2 is a central system, not a bilateral network. In a bilateral network, a bank sends a message directly to another bank, so the header names the other bank. In T2, a bank sends a message to the central system, the system settles the payment, and the system then tells the receiving bank what happened. The sending bank does not need to know how the receiving bank connects, which network it uses or which gateway it prefers. It only needs to reach T2 through ESMIG, and T2 takes responsibility for the rest of the delivery. Inside the pacs.008, the agent fields name the banks that the payment is really for. The instructing agent names the bank that instructs the payment, the instructed agent names the bank that must receive the payment, the debtor agent names the bank that holds the debtor account, and the creditor agent names the bank that holds the creditor account. In a direct to direct payment of EUR 4 million from Deutsche Bank to BNP Paribas, the instructing agent is DEUTDEFFXXX, the instructed agent is BNPAFRPPXXX, and the BAH To is still the T2 service. The header and the payment carry different addresses on purpose. The reply path follows the same rule in reverse. When T2 settles the payment, it sends a pacs.002 status report back to the sending bank, with From as the T2 service and To as the sending bank BIC. It also sends a camt.054 credit notification to the receiving bank, with From as the T2 service and To as the receiving bank BIC. Neither reply is addressed bank to bank. Both replies come from the system, because the system is the party that settled the payment and the party that knows the final result. A bank that waits for a reply directly from the other bank will wait for ever. The technical layer also explains why a multi-addressee payment looks different in the header and in the payment. A branch that sends a payment as a multi-addressee puts its own BIC in the BAH From field, because it is the technical sender, while the pacs.008 instructing agent names the direct participant that holds the account. The BAH To is still the T2 service, and the pacs.008 instructed agent is still the receiving bank. A developer who copies the BAH From into the instructing agent, or who copies the instructed agent into the BAH To, will build a message that T2 rejects, and the test team must check both layers separately. Worked example with numbers: a bank in Frankfurt sends a EUR 3 million payment to a bank in Milan, and the Business Application Header names the T2 service as the recipient, not the Milan bank, because T2 is a central system. Inside the pacs.008 the instructing agent is the Frankfurt bank and the instructed agent is the Milan bank, so the header and the payment name different parties, and that is correct. When T2 settles the payment, it sends a pacs.002 status report back to the Frankfurt bank with From as the T2 service and To as the Frankfurt bank BIC, and a camt.054 credit notification to the Milan bank with From as the T2 service. Failure and recovery: the technical layer fails when a bank addresses the Business Application Header to the receiving bank instead of the T2 service, because T2 will reject a message whose header names the wrong recipient. The recovery is a corrected header and a resend, but the payment has lost time, and if the value date has passed, the payment must be re-dated. A subtler failure is a multi-addressee branch that puts the direct participant BIC in the header From field instead of its own BIC, so T2 cannot tell which branch sent the payment, and the status report goes to the wrong place. The bank must therefore validate the header before sending, with a rule that the From field names the technical sender and the To field names the T2 service, every time. For a business analyst, product owner or subject matter expert, the header requirement must state the rule in one sentence: every message to T2 names the T2 service in the Business Application Header To field, and the agent fields inside the pacs.008 name the banks the payment is really for. The requirement must also state that the reply path follows the same rule in reverse, and must name the messages on each leg, pacs.008 out, pacs.002 and camt.054 back. The test pack must include a payment from a direct participant, a payment from a multi-addressee branch, and a payment with a wrong header recipient, because each case exercises a different part of the addressing rule. Source: European Central Bank, TARGET services; last reviewed 7 November 2026.