Get your taxes done using TurboTax

I take it that the stock is not publicly traded and I assume that you have a gain on sale.

If so, you can use the installment method for reporting the sale. 

https://www.irs.gov/taxtopics/tc705.html

I'm not sure if all versions of TurboTax online support installment sales or not, but all desktop versions do.

Tom Young