57.7.1 The most common way to handle deposits/prepayments/advance receipts is to use a negative invoice to offset the prepayment
Example. client prepays $3,000
Record the $3,000 credit/advance amount as a negative invoice (invoice amount = -$3,000)
Every time you open the Business Contacts -> Invoice tab, you will see the negative amount
Use reports 59, 265, 281 and statements to see negative invoice amounts
When you raise the next invoice for the customer apply the value of the prepaid/credit amount and be careful to reduce the negative amount in the negative invoice by the same amount.
When the negative invoice reaches zero, delete it