What Are NACHA Files?

Ian Berryman
Aug 6
2 min read

NACHA files move funds electronically between bank accounts

If you’ve ever received payroll direct deposit or had a utility bill debit your bank account, there’s a good chance a NACHA file was involved behind the scenes.

But what exactly is a NACHA file — and why does it matter?

In this post, we’ll break it down in simple terms so you can understand what NACHA files are, what they contain, and how they’re used in modern ACH processing.

What Is a NACHA File?

A NACHA file (also called an ACH file) is a structured plaintext file that contains instructions for processing ACH transactions. It tells the bank:

Who is paying
Who is receiving
How much money is moving
Which bank accounts are involved

The file follows formatting rules published by NACHA (National Automated Clearing House Association), the organization that governs ACH in the United States.

What Does a NACHA File Look Like?

A NACHA file is made up of fixed-length lines (records) 94 characters long. Each line serves a specific purpose within the file.

A basic file includes:

File Header Record – identifies who is sending the file
Batch Header Record – groups related entries (e.g. payroll batch)
Entry Detail Records – one per transaction (debit or credit)
Addenda Record (optional) – adds extra info like invoice details
Batch Control Record – summarizes batch totals
File Control Record – summarizes entire file totals

These records follow strict field lengths and positions, meaning even a single misplaced digit can result in file rejection by the bank. If you want to see examples of real NACHA files, check out our post: Common NACHA File Examples

Common Use Cases

NACHA files are used to:

Pay vendors via ACH credit
Collect payments from customers (ACH debit)
Process payroll through direct deposit
Send refunds, expense reimbursements, or rent payouts
Validate bank accounts using prenotes
State and federal government payments for tax refunds, Social Security, etc

Do I Need to Create NACHA Files Manually?

Usually not. You’ll use a tool like ACH Pro to generate NACHA files for you.

Manual creation is difficult and risky because of the complexity of the files and the possibility that mistakes will affect real dollars and bank accounts.

Instead, most businesses use NACHA-compatible software like ACH Pro that lets you:

Import payment data from QuickBooks or spreadsheets
Store and manage recipients
Create fully formatted files ready for upload

Final Thoughts

NACHA files power billions of transactions and trillions of dollars in the U.S. every year. While it may look like a wall of text to the untrained eye, it’s a powerful and standardized way to move money safely and efficiently.

Whether you’re paying employees, billing customers, or sending refunds, understanding what a NACHA file does — and using the right tools to create it — helps you avoid errors, reduce friction, and streamline your payment operations.