The ACH Guide for Developers

How to Use This Guide

The ACH Guide for Developers is designed to serve as a handy quick reference for developers. You may not understand how the ACH Network works or why, and you may not have read the Nacha Operating Rules, yet you have been tasked by your organization to code a Nacha file. This guide is intended to help you.

This guide will help familiarize developers — who are not Rules experts — with the basics of ACH and provide a general understanding of how the ACH Network operates. Additionally, this guide includes file formats, scenarios for using specific data elements, and information on where to find details in the Rules.

This guide is a high-level overview and will not contain all details or describe all situations. The Rules are available at and contain the full specifications, as well as more detail on the relevant data elements. Where appropriate, the relevant section of the Rules is referenced in this guide.

This guidance was developed by Nacha’s Payments Innovation Alliance, which is a diverse membership group of domestic and international organizations uniting to support payments innovation through discussion, debate, education, networking and special projects. The Alliance incubates new ideas and initiatives to advance the industry.