Account for FedACH vs. EPN ACH operator differences when building an ACH integration

Steps

1. Recognize the ACH network has two operators — the Federal Reserve's FedACH and The Clearing House's EPN — and your ODFI's relationship with one of them, not your own choice as an API client, determines which operator processes your outbound files.
2. Understand operator interoperability: FedACH and EPN exchange files with each other multiple times daily, so a transfer originated through a FedACH-connected ODFI can still reach an RDFI that only uses EPN without any special handling on your part.
3. Don't assume every financial institution preserves the trace numbers you submit — confirm with your bank/API provider whether trace numbers are preserved end-to-end, since this affects how you correlate incoming returns to the transfers you originated.
4. Design around FedACH's asynchronous, file-batch submission across three same-day windows and six future-dated windows per business day, building operational monitoring around window cutoffs rather than expecting per-transaction real-time acknowledgment.
5. Plan for rare but real network data-quality issues, such as a transfer being returned more than once or a return arriving with incorrect original transaction details, since the network itself doesn't store authoritative transfer state.