What does AC01 mean in ISO 20022?

AC01 is Incorrect Account Number in the ExternalMandateReason1Code code set: Format of the account number specified is not correct

Where does AC01 appear in a message?

For example in pain.010, element UndrlygAmdmntDtls/AmdmntRsn/Rsn/Cd.

ExternalMandateReason1Code

AC01 Reason Code: Incorrect Account Number

Written and maintained by ZagTrader. Last reviewed 21 October 2026. How this page is sourced and checked

AC01 means incorrect account number in the ISO 20022 mandate reason code set. Format of the account number specified is not correct

Code: AC01
ISO name: IncorrectAccountNumber
Status: Registered
Last updated: 2010-11-01

Official definition

Format of the account number specified is not correct

Definition from the ISO 20022 External Code Sets, 2Q2026 (published 28 Aug 2026).

Messages and fields that use ExternalMandateReason1Code

Message	Element path
pain.010	UndrlygAmdmntDtls/AmdmntRsn/Rsn/Cd
pain.011	UndrlygCxlDtls/CxlRsn/Rsn/Cd
pain.012	UndrlygAccptncDtls/AccptncRslt/RjctRsn/Cd

AC01 in other code sets

AC01 questions

What does AC01 mean in ISO 20022?: AC01 is Incorrect Account Number in the ExternalMandateReason1Code code set: Format of the account number specified is not correct
Where does AC01 appear in a message?: For example in pain.010, element UndrlygAmdmntDtls/AmdmntRsn/Rsn/Cd.

All ExternalMandateReason1Code codes · ISO 20022 code sets

The ISO 20022 code names and definitions on this page are reproduced from material published at iso20022.org under the ISO 20022 Intellectual Property Rights policy. This is not the official source: the up-to-date ISO 20022 standards and repository material are published only at iso20022.org. Explanations in our own words are by ZagTrader. ZagTrader is not affiliated with or endorsed by ISO or Swift.