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AC01 means 'Incorrect Account Number'. The account number or IBAN provided for the beneficiary is either syntactically invalid or does not exist at the beneficiary bank. The payment is rejected and funds will be returned to the sender. Fix the account number and resend.
AC01 is an ISO 20022 ExternalReturnReason1Code returned in a pacs.002 status message when a bank in the chain cannot validate the beneficiary account number. It is the most common SWIFT reject code after sanctions issues.
Common causes: IBAN transposed digits (the IBAN check digit will catch this), account number in a wrong format for that country, account number that once existed but was closed before the IBAN was discontinued (use AC04 for closed accounts — some banks return AC01 in both cases), or a BIC pointing to the wrong branch.
What to do: ask the beneficiary to provide the correct IBAN and BIC directly from their bank's official onboarding letter or statement. Do not rely on an IBAN the beneficiary typed from memory — transcription errors are the leading cause of AC01.
Funds return to the sender within 2-5 business days. Original correspondent fees are typically not refunded. Track the UETR on Ohmyfin to confirm the payment is returning and to see which bank rejected it.
AC01 means 'Incorrect Account Number'. The account number or IBAN provided for the beneficiary is either syntactically invalid or does not exist at the beneficiary bank. The payment is rejected and funds will be returned to the sender. Fix the account number and resend.
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