When adding items to the prepayment tool, providing the invoice has been posted to the the P&L, the prepayment tool moves it from the P&L to the prepayment balance sheet account and then prepays one month instantly. However, we have situations where the prepayment does not need to start until 2-3 months later for example, and also the other way, we may need to make an initial prepayment which covers 2 months instead of one because the invoice was not received until later.
Currently as it stands, it is easier to do prepayments manually via a spreadsheet than using the prepayment tool.