BACS Reason Codes Explained
A reason code is the answer a bank sends back after it has processed your submission: it says that a Direct Debit instruction was rejected, that a collected payment was returned, or that an existing instruction changed. The three code sets follow the Direct Debit lifecycle — setting up, collecting, and amending — and none of them is a comment on the layout of your file.
ARUDD codes
Automated Return of Unpaid Direct Debit — the codes returned when a collected Direct Debit cannot be paid.
AUDDIS codes
Automated Direct Debit Instruction Service — the codes returned when a new Direct Debit instruction fails validation.
ADDACS codes
Automated Direct Debit Amendment and Cancellation Service — changes and cancellations against an existing instruction.
Frequently asked questions
- What is a BACS reason code?
- A short code a bank returns against a Direct Debit instruction or a collected payment to say why it was rejected, returned or amended. It describes the payer's account or the mandate — not the layout of the file you submitted.
- Can BACS Check fix a reason-code rejection?
- No. Reason codes come back after the bank has accepted and processed your file, and they describe a banking or mandate issue. BACS Check repairs file-format defects: record width, line endings, the UTL1 trailer label and the totals.
- Where is the complete list of codes?
- The full sets are in your bank's Originator's Guide. The pages here cover the codes an originator meets most often, with the meaning the bank assigns to each one.
- My submission file will not upload at all — is that a reason code?
- No. A file the bank cannot read, or that is rejected on structure, is a format problem rather than a reason code, and it is the one worth repairing before you resubmit.
These codes describe why a Direct Debit mandate or payment was rejected — a banking/account issue, not a file-format problem. If instead your BACS submission file is malformed and won't upload to the bank (wrong record length, bad line endings, a UHF1/UTL1 mix-up, or totals that don't reconcile), that's what BACS Check repairs — paste or upload your file here →