If you imported an Excel or CSV file and have not yet clicked the button ‘Go To Create ACH File Page’, your transmission file can still be changed. If you click on Reports->Untransmitted Records, and you see the current transactions listed, you can go to the Home tab, click on the little black house icon, and you can ‘Add a Record’ to include one more transaction before clicking ‘Go To Create ACH File Page’.
If you have created the ACH transmission file, it will not be possible to add another transaction without re-doing the entire batch.
At the top of the page, click on Reports->Import Logs and highlight the top import row blue (by clicking on the little triangle at the far left). Then, click on the red “X” to delete that entire import. Once the import log is deleted, then you can re-import data or re-integrate with QuickBooks to create the transmission file again.