Well, can't help much, as we're not given the "interest collection procedure";

like, is interest SHOWN (added to balance) at every transaction, or monthly

only, or annually only.

If monthly, then you'd need the monthly equivalent to "8% compounded annually",

which is determined this way: (1 + r)^12 = 1.08 ; solve: r = .006434...:

so as example, $1000 owing for 1 month = 1000 * .006434 = $6.43

I'll recommend you use the "Julian date" (day of the year; like Feb. 22 = 43),

which will greatly simplify the interest calculation; example:

Code:

DATE J.DATE TRANSACTION INTEREST BALANCE
Jan.10/11 10 +5000.00 5000.00
Feb.12/11 43 -5036.16 36.16 .00

The interest calculation: .08/365 * (43-10) * 5000 = 36.16

Hope that helps....