Compute a $25.00 late fee and Intrest after 10 days

How often do you want to compound the interest?

=(((25*0.18)/365)*5)
The last number, 5 is the number of days over 10, you want to charge interest for. The 365 is assuming you want this daily.
I'm not going to compound it, as that would be utterly ridiculous. We are talking about far less than a penny.

The solution for the above, if we're talking about 5 days, is .06 cents.
18% interest on $25 is $4.50 for the entire year.

Are you really sure you want to go through all this trouble for pennies?
I can't imagine a small business actually going ahead and charging this. If you were a large business, all these calculations would be done for you in your company software.

This is probably not the most accurate formula in the world, but close enough for everyday application.

Is this for a homework assignment where you need much more exacting compounding and time retrictions?

Because honestly, if this is a real world problem, it's just not worth it.

Hello,
As a director on the Board of Directors, our governing documents states that any HOA payment ($35.00) that is not received by the tenth of the month, a late fee of $25.00 will be added to the account. Also we are allow to charge 18% per year interest on the unpaid balance, starting after the tenth. Hence is why we are needing to be able to Exccel (auto) charge a $25.00 late fee if not received by the 10th of the month, along with an 18% (1.5%) per month/per day interest on the unpaid amount.
Hope this clarifies . Please let me know if the formula that was publish will work in this situation.
Thanks!

Hello,
As a director on the Board of Directors, our governing documents states that any HOA payment ($35.00) that is not received by the tenth of the month, a late fee of $25.00 will be added to the account. Also we are allow to charge 18% per year interest on the unpaid balance, starting after the tenth. Hence is why we are needing to be able to Excel (auto) charge a $25.00 late fee if not received by the 10th of the month, along with an 18% (1.5%) per month/per day interest on the unpaid amount.
Hope this clarifies . Please let me know if the formula that was publish will work in this situation.
Thanks!