Why should I use transmittal invoices?

Using transmittal invoices in Payroll means that the changes that you make to invoices that are created in the Payroll application will also balance with the General Ledger. Sometimes the invoices that you enter through Accounts Payable are not being balanced with the liability account that are coming from Payroll. A transmittal invoice may be helpful for several reasons:

Documentation. It's a formal record of the goods or services being transmitted and documentation can be useful for tracking purposes. You can also use it to resolve and troubleshoot issues.
Clarity. A transmittal invoice outlines the terms of the transaction. This, too can help resolve issues that may arise in the future.
Legal. In the event of a dispute, a transmittal invoice can service as evidence of the transaction.