Guides
Payment rules, written plainly.
Reference guides on ACH, card networks and phone payments, each with primary sources.
Every guide
Start with the question you have.
- REF ACH Return Codes Every Nacha return code, how long the bank has, and what to do next.
- REF ACH Returns, Reversals and Disputes Who sends an entry back, by when, and what the originator may do next.
- REF ACH vs Wire How ACH and Fedwire differ on timing, limits and reversals, from Fed and Nacha sources.
- REF Mastercard MATCH List What Mastercard's own rules say about MATCH listings, reason codes and removal.
- REF Nacha File Format How an ACH file is built, record by record, with a fictional sample.
- REF Nacha Rules What the Nacha Operating Rules require, from SEC codes to the 2026 rule dates.
- REF PayPal Holding Funds? Holds, Reserves and What to Do Why PayPal, Stripe and Square hold money, for how long, and what their terms allow.
- REF What Is MOTO? Taking Card Payments Over the Phone What MOTO means, and what PCI SSC and Nacha require when payments come by phone.
- REF Visa VAMP Visa's Acquirer Monitoring Program in Visa's published numbers, with Mastercard's program beside it.