How to apply late fee?

I have searched and found nothing that can help me out this.

OK, I already have the following table setup:

tblPayments
PmtID
PmtDate
pmtAmount
LatePmtFee
loanID
etc...

I lend someone an x amount of money to pay me an x amount of money every week over a period of time. The interest will be included in this payment already.

Now, I will charge that person and x amount as a late fee when he/she doesn't have the money for that week.

What I can't figure out is how to show on the report how much somenone owes plus what is the late fee and how much it is due on the next payment for the following week.

I you need more information let me know.

Thanks

I was going to post this on the report forum and by mistake I posted here, sorry.