One often issues advance invoices to clients for estimated costs, but what if the advance payment exceeds the actual cost of the services provided?
Booking an advance payment
Firstly, create an advance invoice as usual and then book it when the payment is received.
Over time, services will accumulate in the dossier until the mandate can be charged.
Create an invoice
When that time comes, create an invoice for the accrued services. There is no need to print this invoice and it should not yet be booked, since the balance is still in the client's favour.
Credit the advance payment
Before the invoice can be booked, the advance invoice must be credited. This allows the advance payment to be booked to the "Transitory Items" account, from whence it can be freely distributed among all the mandates in the client's dossier.
Booking the invoice
Now the final invoice can be offset against the credit balance. When booking, it should be recorded how the credit from the advance payment has been used, and thus resulted in a credit balance remaining in the "Transitory Items" account. The balance in the "Transitory Items" account may be used for other mandates.