If you already have an ACH account with your bank and you want to create ACH/NACHA file to process Customer Payments / Vendor Direct Deposit using QuickBooks Online/ QuickBooks Desktop data like bills created in QuickBooks, customer invoices created in QuickBooks, you can use Intuit approved third party applications.

Customer payment NACHA file can be created based on QuickBooks customer invoices with no additional data entry is also supported.

See Intuit's app center at https://apps.intuit.com/app/apps/appdetails?shortName=app-b7rhf97pmg.