Calculating Overtime Hours for each Day on a 40+ Overtime per Week Basis

I'm having trouble with my Overtime Hours column (I).
I can't figure out how to get it to show just the overtime for that day.
I have attached the xlsx file as well as a photo of the table as is.

The formula for that column is: =IF(ISBLANK(D20),0,(MAX(H20-40,0)))
I want it to subtract the previous cell before it, but every time I do it returns a value error with this formula:
=IF(ISBLANK(D20),0,(MAX(H20-40,0)-I5:I6)) Then the I6 increases

The ultimate goal is for a spreed sheet that can calculate employee wage with a single employee that has two separate wages
that shares the same set of 40 hours for that week in a biweekly setup with an on call bonus added at the end of the week. If I can get this overtime figured out I think I got the rest of it. I might have trouble with the job codes I'm not sure yet. I'm going to change them to numbers when I get to them, the current strings are for easy reference at this point.