Comerica NACHA file requirements
Comerica accepts NACHA-format ACH files through Comerica Business Connect (Comerica Treasury Payments (import/export)) but does not publish its file specification. Here is what is public, and exactly what to request from the bank.
Independent documentation. Not affiliated with or endorsed by Comerica.
Before you upload, run the file through the free ACH file validator. It checks the structural rules and Comerica's documented quirks in your browser; the file never leaves your computer.
How Comerica ACH file upload works
- Comerica does not publish a NACHA file specification publicly. Only the treasury services legal agreements are public.
- ACH file import and export run through Comerica Treasury Payments inside Comerica Business Connect.
Source: Assembled from public pages and indirect sources; confirm everything with the bank: Comerica Treasury Management Services Master Agreement (public legal document; no file layout), checked July 2026. Reference. Banks change their requirements; your bank agreement and portal are the authoritative reference.
What to request from your Comerica treasury contact
Ask for the bank's NACHA file layout or ACH origination guide by name; every bank has one even when it is not public. While you wait, the format itself is the industry standard documented in our NACHA format guide, and a file that passes the validator is structurally correct under Nacha rules; what remains are the bank's own settings below.
Four values are assigned per customer and only the bank can tell you them: your Company ID (often not just your EIN), the exact immediate origin value they expect in the file header, whether your agreement is set up for balanced or unbalanced files, and your cutoff times and settlement option. Get them in writing before the first upload.
Building the file
Most accounting software, including QuickBooks and Sage 50, cannot export a NACHA file directly. If your system exports one and Comerica still rejects it, the validator will usually name the exact line and field. If the reason will not yield, the format setup service works it out with you. This software formats and checks files only. It moves no money; funds move solely through your own bank under your agreement with them.