calculate late charge based on specific date(s)

[Robert Morris]

Hi,
I'm developing a database for an apartment complex and
one of the queries is based on tenant personal info and
tenant rent that is due that month, I have it set where I
can calculate the total rent due and any partial payments
made. What I need to do now is to calculate a late
charge if the total payment is not received before a
specific date(s) each month. Any suggestions?

Thanks

Robert