This is the third part of my three part question. The big picture of what I need to accomplish is this: take utility bills, break out the various tax amounts reported on them, total them and then report those amounts by quarters.

Taxes are reported many different ways including combined in lump sum amounts. I need to break out the individual taxes from those lump sum statements. This is relatively straight forward; however, sometimes the tax rate will change in the middle of the billing period. How do I factor that in?

I currently have fields that capture the start and end dates of the billing period as well as the start and sunset dates of optional taxes. The only solution that is coming to mind is to flag situations where the sunset date falls between the start and end dates of the billing period, kick them out, and handle the calculations by hand, and then enter those numbers as if the bill had been broken out by tax in the first place. However, this requires a lot of user intervention. Any suggestions that would avoid user intervention will be gratefully received!