What Is a NACHA File?
A NACHA file is a standardized text file used to send ACH (Automated Clearing House) payments through the U.S. banking system. If your business pays vendors, employees, or contractors electronically, there is a good chance a NACHA file is involved — even if you have never seen one.
NACHA stands for the National Automated Clearing House Association, the organization that sets the rules for ACH transactions. The file format they define is how banks communicate payment instructions to each other.
Why Should You Care?
If you are a small business making recurring payments — payroll, rent, vendor invoices — ACH is almost certainly cheaper and faster than paper checks. A single ACH payment costs pennies compared to $4–12 for a physical check (when you factor in printing, postage, and reconciliation time).
The catch? To send ACH payments directly through your bank, you need to create a properly formatted NACHA file. And that format has strict rules.
How Is a NACHA File Structured?
A NACHA file has a hierarchical structure with five record types:
- File Header (1 record) — Identifies the file originator and destination bank
- Batch Header (1 per batch) — Groups related transactions (e.g., all vendor payments for the week)
- Entry Detail (1 per payment) — The individual payment: account number, routing number, amount, recipient name
- Batch Control (1 per batch) — Totals and counts for the batch
- File Control (1 record) — Totals and counts for the entire file
Every record is exactly 94 characters wide. Fields are fixed-width and position-dependent. A single misplaced character can cause your bank to reject the entire file.
The Problem for Small Businesses
Most small businesses face an awkward gap:
- Bank portals let you send one payment at a time but do not support batch files
- Enterprise treasury software handles NACHA files but costs $500–2,000/month
- Spreadsheet workflows are error-prone and tedious
If you are making 10–200 payments per month, you need something in between.
A Better Way
FiSTWorks lets you create, validate, and transmit NACHA files directly to your bank — without the enterprise price tag. Import your payment data, validate it against the full NACHA specification, and send it via secure SFTP.
No per-transaction fees. No middleman. Your bank relationship stays yours.