An ACH file will usually contain only the transactions that you specify.
Example: If you have to pay five contractors $100 each, the file will contain the five 'credit' transactions--one for each payment. Your bank will debit your account for the offset, which in this case would be $500.
If a bank requires an offset record (also known as a 'balanced file'), then the file would contain the five transaction records (credits) PLUS an additional record for a $500 debit.
To enable offset records in your transmission files, from the ‘Home’ tab, select the ‘ACH File Setup’ icon, select the ‘Advanced Setup’ radio button on the second page, and click through to Screen 4 of 7. Check the box ‘Enable offset record’ and fill in the requested data. You may leave the Offset ID blank (example below).