Adding new records to table in access

[easg]

Ok this is what I have, I have a table that has the invoices for all costumer, this documents has end dates, after this a fee is billed based on the remaining amount, similar to a bank accout card that every month gives you interest, this, based on the date which is my criteria, how can I make the database to register this automaticaly via visual basic running a module every month? I have in this table: [Costumer_ID],[Doc_number],[doc_type][Date],[Total_amount]

Note:[doc_type] can be Invoice or payment then I create two queries one for invoces one for payment and this two merge into another query that calculates the diference between both, that is the remainig amount, and based on this is that I want to calculate the fee, the fee can be stored in the same table with another doc_type, but it must have [Costumer_ID],[Doc_number],[doc_type][Date],[Total_amount] doc_number can be ramdom in this case.