The year its paid is the years tax return you put it on.  Paid in 2017 goes on 2017 tax return.

Ok great thank you. So I need to go back and find the tax I paid for the 2015 year in 2016 then, since I pay my taxes w the refund after filed.  Sound right?   Thank you

Yes you would have paid the second 2015 installment in 2016, so it would go on the 2016 return.