Where is my NACHA file

For Payroll the file downloads onto your computer unlike how AP attaches the file to the batch. 

Using the Payment Batch screen, you can Export or Export as Prenote using the more menu.  Be sure that you allow pop-ups for the Acumatica site because as noted above, the file will download to your computer, not attach to the Payment Batch record.

Be sure to look in the Files area in the upper right corner of the Payment Batch form.

​@kstrobel The ability to generate a NACHA (ACH) payment file is built into the standard Acumatica Payroll module and is supported without requiring any additional customization or file imports.

To ensure the feature is configured correctly, please review your Payment Method settings:

1. Open the Payment Method record.
2. Go to the Settings for Use in PR tab.
3. Confirm that Create Batch is selected as the processing option.
4. Verify that the Export Scenario is set to Export PR Payment to ACH.

Hii ​@kstrobel , The NACHA (.txt) file is generated when you export the payroll payment batch. It isn't stored within Acumatica for later viewing—it is downloaded by your browser. If you don't see it, check your browser's Downloads folder/history and verify that the ACH export completed successfully.