Handle ACH returns (R-codes) and notifications of change (C-codes)

Steps

1. Receive the return or NOC file from your ODFI, typically delivered in a NACHA-formatted file; parse the Return Addenda Record (Type 99) to extract the return reason code
2. Map R-codes to action categories: administrative errors (R02 invalid routing, R03 no account) require account correction; authorization errors (R05, R07, R10, R29) may indicate fraud and require customer contact; settlement failures (R01 NSF, R09 uncollected funds) may be retried per NACHA rules
3. For R-codes that permit retry (e.g. R01, R09), comply with NACHA's retry rules: a returned entry may be reinitiated a limited number of times within defined timeframes; consult current NACHA rules for exact counts and windows
4. For Notifications of Change (NOC), parse the C-code addenda: C01 (incorrect account number), C02 (incorrect routing number), C03 (incorrect account number and routing number), C05 (incorrect transaction code), etc.
5. Update your stored account data with the corrected information from the NOC addenda within the NACHA-mandated timeframe (six banking days or prior to next debit, whichever is earlier) and use corrected data on all future entries