Deduct Agency Commission

I have an agency that wants to have their 15% deducted from the invoice total.

The account used for the order needs to be a separate account that is linked to the agency.  You do that by creating an agency account from Accounts by clicking the File menu then “New Agency”.  After that, click to the account used for the order and select the agency on the Agency drop-down list.  Then on the order select Net for billing type.
Once you’ve done this the invoice will show the total charges, the 15% commission , and the net charges (the total minus the 15% commission).