Can you tell me how you did this so that QB actually does the math? I ran into the same problem, and figured out a way to edit the template to add the credit to the invoice in print view, however it still doesn't do the math. To use your example of a $200 invoice with a $150 credit, mine would show $200 as the sub total, with a $150 credit, but the total at the bottom is still $200, not $50 like it should. It's like QB doesn't do the math on the printed version, only on my screen view.