# How to allocate a prepayment against a sales order using an existing credit invoice

KB67

A Customer has an overpayment or pre-payment credit sitting on their account, and you would like to allocate this credit as a prepayment against a new Sales order:

1. Enter prepayment receipt against the Sales Order just like normal for the amount they want to pay off
   1. Make the Receive into account a suspense account so that it does not appear in the P & L
2. Enter a receipt for the original credit, putting negative amount at the top
   1. Make the Receive into account the same as above
   2. This will take the suspense account back to zero and clear out the original credit

The reason we can’t put $0 at the top is because the prepayment checks only look at the value of the receipt, not the way it was allocated, so tricky allocations will cause a problem.