On the annual statement, the advance payments are totaled up and compared to your actual consumption. If you have consumed far less than originally estimated and paid in advance, you will have a positive (+) credit. In this case, you will receive some money back from us. If you have paid less, you will have a negative (-) credit (i.e. a debit), which means you will have to pay us outstanding amounts. Please note that the 12th advance payment is, as a matter of principle, not included in the "advance payments made" and only becomes due with the annual statement. The debit amount should consequently correspond to a normal advance payment. If the debit is far higher than the 12th advance payment, the cause lies in a higher consumption, for example.