The situation: A user put a personal charge on company card by accident.  He submitted the expense report with that charge and marked it as personal expense. The accounting team talked to the HR team and his pay cheque was deducted.  Later on he returned the item.  The charge came through into Concur as a negative charge.  He submitted the expense report with the negative charge and marked it as personal.  Concur then paid that amount into his personal banking account.  This all makes sense and equals out.

The loop hole:  If the user puts a $25 personal charge on company card the charge will go into Concur.  A day or so later he decided to return the item.  The negative charge will appear in Concur as well.  The user then submits his expense report with both the positive and negative charge.  The accounting team will see that it is offsetted so the accounting team doesn't tell HR to deduct his pay but that will mean Concur will pay the user the $25 into his personal bank account. 

How do I stop the payment of a negative expense that is marked as personal?  Unfortunately an audit rule does not stop the payment but I need all charges (whether it's positive or negative) to go through Concur so that it shows in the books.