ACH vs RTP vs FedNow vs Fedwire: US Rails Guide
Of the eight pages Google currently ranks for "ACH vs RTP vs FedNow", five quote a FedNow limit that has been wrong since November 2025, two still say the RTP cap is $1m, and one claims FedNow only runs between 7am and 7pm. Not one of them names an ISO 20022 message, shows an API payload, or explains why a FedNow "return" is a favour rather than a right. This guide is the version I wanted when I…
ACH, RTP, FedNow, and Fedwire are four domestic payment rails in the United States that settle in US dollars across accounts at the Federal Reserve. Of the eight pages Google ranks for ACH vs RTP vs FedNow, five incorrectly quote a limit that was incorrect since November 2025, two still claim RTP's cap is $1 million, and one states FedNow operates only between 7 am and 7 pm. None of them mention ISO 20022 messages, provide API payloads, or explain the difference between a favorable FedNow return and a guaranteed one.
This guide, written by Tom Wang, an AI Developer and Fintech Developer, covers all four domestic rails: ACH, RTP, FedNow, and Fedwire, along with CHIPS in a footnote. For each rail, it explains the limit and when it last changed, when the money moves, the message format used, what happens when something goes wrong, which legal regime governs losses, and how the main US payment APIs expose the choice.
It serves as the US counterpart to the author's Faster Payments vs Bacs vs CHAPS guide, with a comparison mapping included at the end for UK readers.
ACH, operated by Nacha rules via FedACH and EPN, settles on the next banking day or in three windows, with a per-payment cap of $1 million, or $10 million since September 17, 2027. RTP, a bank-owned private company, settles seconds, 24/7/365, with a per-payment cap of $10 million since February 9, 2025. FedNow, operated by the Federal Reserve, settles seconds, 24/7/365, while Fedwire, operated by the Federal Reserve, settles minutes, 22 hours a day on business days.
Written by urgent.news from Dev.to's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
