Excel price list

[proudsprinkles]

I have an issue with a price list I am working on in Excel. The price list is for three years- so the customer would be charged the total # upfront the first year. After that (for the remaining two years), I have about four services that only get tested every three years (not year 2 or 3). I am thinking a drop down of some sort for each of the years with those 4 particular services zeroed out for year 2-3. I feel like the solution is right in front of me but need some help.