R04 | Invalid account number
This code indicates the account number provided is invalid or fails the RDFI’s account validation requirements.
What This Code Means
R04 is used when the receiving institution determines the account number is invalid for posting the ACH entry. This can mean the number is the wrong length, fails internal checksum or validation rules, or otherwise does not conform to the RDFI’s accepted account numbering structure. While similar to R03, which reflects inability to locate an account, R04 emphasizes invalidity of the account identifier as submitted. This return reflects account validation at the RDFI, not a temporary network or processing delay. It also does not imply the receiver acted in bad faith; it indicates the account identifier did not meet requirements for posting.
Where Users Usually See This Code
- Bank draft or ACH debit failures in billing systems
- Payment processor return code dashboards
- Returned entry notifications in reconciliation files
Why This Code Appears
- Account number length or format does not match RDFI requirements
- Digits were entered incorrectly or truncated
- Leading zeros were omitted where required
- Internal account validation checks failed at the RDFI
What Typically Happens Next
- The entry is returned as invalid with R04
- The originator records the failure and may request updated account details
- Repeat attempts with the same information typically return again
What This Code Is Not
- It is not insufficient funds (see R01)
- It is not a closed account status (see R02)
- It is not an authorization dispute (see R05/R10)
Troubleshooting Checklist
- □ Confirm the account number was captured exactly as provided by the account holder
- □ Review whether formatting (such as leading zeros) could affect validation
- □ Compare against previously successful transactions for consistency
- □ Log the return code for auditing and future prevention
Notes And Edge Cases
R04 outcomes can be sensitive to formatting rules such as leading zeros and institution-specific account numbering patterns. Some RDFIs may map certain validation failures to R03 rather than R04, so patterns can differ by institution. If an account was recently opened, timing and internal system synchronization may affect validation outcomes during early posting windows. In some cases, different SEC codes or entry contexts may interact with the RDFI’s validation logic.