Hi there, 

I appreciate you posting in the Community. I'll be happy to share more info about billable expenses.

I want to make sure I'm on the same page as you. How are you adding/entering the mark-up to the billable expenses? For reference, here are the steps to entering billable expenses:

1.     Create an expense transaction on the Bill, Expense, or Cheque window.
2.     In the Account or Product/Service field, choose the expense account or product/service for the item or service you purchased for the customer.
3.     Enter the cost of the items in the Amount field.
4.     If the cost is less than the total amount of the transaction, enter a separate Detail line for each amount.
5.     Enter a Description of the items.
6.     Note: This description will appear on the customer's invoice.
7.     Select the customer to be billed for the item or expense from the Customer drop-down.
8.     Select the Billable checkbox.
9.     Enter a Markup percentage.
10.     If you need to charge tax for the item or service, select the Tax checkbox.
11.     Note: The Tax column becomes available if the Billable and Tax features are turned on.
12.     Save the transaction.
     

For more info, check out this helpful article which has more info on billable expenses. Let me know if you've got questions.