AC01 Reason Code: Incorrect Account Number

Official definition

What it means in practice

In a pacs.004 payment return, a return reason code explains why funds that were already settled are being sent back. It sits in TxInf/RtrRsnInf/Rsn/Cd, and bank statements (camt.053, camt.054) repeat it in RtrInf/Rsn/Cd.

The account number in the payment does not exist at the receiving bank or is not in a valid format. With an IBAN this usually means the check digits pass but the bank cannot find the account, or the IBAN belongs to a different bank than the one the payment was routed to.

It is one of the most common reasons a cross-border payment is rejected or returned, and it almost always comes from data entered at the start of the chain.

What to do

• Check the IBAN or account number against the beneficiary's invoice or a confirmed statement, not against an earlier payment that may have copied the same mistake. The IBAN checker catches typing errors in the check digits and length.
• Confirm the account is held at the bank identified in CdtrAgt (MT field 57a). A valid IBAN sent to the wrong bank is also reported as AC01 by many banks.
• Fix the data in the payment order and send a new payment with a new reference and a new UETR. A rejected or returned payment cannot be repaired and resent under its old identifiers.

Messages and fields that use ExternalReturnReason1Code

Related reason codes

• AC02Invalid Debtor Account Number
• AC03Invalid Creditor Account Number
• AC04Closed Account Number
• AC06Blocked Account
• AC07Closed Creditor Account Number
• AC13Invalid Debtor Account Type
• AC14Invalid Agent
• AC15Account Details Changed

AC01 in other code sets

• AC01 in ExternalStatusReason1Code
• AC01 in ExternalMandateReason1Code
• AC01 in ExternalVerificationReason1Code

AC01 questions

What does AC01 mean in ISO 20022?

AC01 is Incorrect Account Number in the ExternalReturnReason1Code code set: Format of the account number specified is not correct

What should I do when I get AC01?

Check the IBAN or account number against the beneficiary's invoice or a confirmed statement, not against an earlier payment that may have copied the same mistake. The IBAN checker catches typing errors in the check digits and length. Confirm the account is held at the bank identified in CdtrAgt (MT field 57a). A valid IBAN sent to the wrong bank is also reported as AC01 by many banks. Fix the data in the payment order and send a new payment with a new reference and a new UETR. A rejected or returned payment cannot be repaired and resent under its old identifiers.

Where does AC01 appear in a message?

For example in pacs.004, element TxInf/RtrRsnInf/Rsn/Cd.