I would like to find a spreadsheet that will allow ...

I would like to find a spreadsheet that will allow my parents to record their prescription purchases and calculate the expediture against their Medicare coverage allowance.  There is such a thing as a "donut hole" that occurs when the insured spends a specific amount total amount of on RX and then they are 100% responsible for their purchases.  After they reach another spending point, Medicare coverage kicks in again and pays 85% of the cost of subsequent purchases.

I'm not sure exactly how it works, but hoped that there may already be a workbook out there to