I'm developing an invoicing system, but I'm struggling to find the right terms to use. (The application itself is in another language, but the database terms are all in English.)
Customers get an invoice every January, with estimated costs for the services they will use.
Then, in December, they get an invoice with a correction (may be debit or credit).
I will define the first invoice as 'advance', but what would I call the second invoice? Settlement? I need to make this distinction, because the system has to take the advance payment in consideration when issuing a new (...) invoice.