When taking payment with a house account the option to charge a credit card is not presented.
This is because house accounts are invoiced or charged in some other way.
This proves to be a difficult situation as there is no way to enter a tip for the order.
If a tip has been collected some other way and you would like it to be entered into your reporting so it can be split amongst your staff follow these instructions:
1. Total the amount of tips you've collected from house accounts
2. When doing a cashdrop at the end of the day enter this total into the "Tip Jar Amount" field of the cashdrop screen.

This will add the Tip total to your reporting, when running a tip report this amount will be included and split amongst your staff.