Reference
Payment file reference
Record layouts, code lists and validation rules for the files NACHA Navigator reads: NACHA (ACH) files, BAI2 balance reports and X9.37 image cash letters.
Last updated
The layouts and code lists on these pages come from the same tables the viewers use to read and check a file, so the pages and the tools agree. When you have a file in hand, open it in a viewer to see the same fields labeled with your own data.
NACHA (ACH) files
The fixed-width files banks exchange to move ACH payments: payroll, vendor and bill payments, and the returns that come back.
Open a file in the NACHA Viewer, or build one with the NACHA Generator.
Record layouts
NACHA file format
What every field of every record holds: its position, length and format, whether it is mandatory, and the codes that go in it.
Validation
NACHA file errors
Why a file gets rejected: each error and warning the NACHA Viewer reports, what it means and how to fix it.
Code list
ACH transaction codes
What the two digits in positions 2–3 of an entry mean: the account, credit or debit, and whether it is a live entry, a prenote, a zero-dollar entry or a return.
Rules and tool
ACH reversal
When an entry or a whole file may be reversed, and how the reversing file is built from the original. Build one in your browser.
BAI2 balance reports
The balance and transaction reports banks send their business customers, account by account.
Open a file in the BAI2 Viewer.
Code list
BAI2 type codes
What a three-digit type code means: its description, whether it reports a balance, a total or a single transaction, and whether it is a credit or a debit.
Record layouts
BAI2 file format
Every record from the 01 file header to the 99 file trailer, field by field, with funds types, continuation records and control totals.
X9.37 image cash letters
The files of check images and MICR data that banks exchange to clear checks electronically.
Open a file in the X9 Viewer.
Record layouts
X9.37 file format
Every record type of an image cash letter, from the file header to the check images, with its fields.
Sample files
Made-up data in real formats, for learning a format or testing your own software.
Downloads
Sample files
Sample NACHA, BAI2 and X9.37 files to download or open in the viewers, with what each one shows.
Missing a reference you need, or found a mistake? Email us.