My parents have to pay my federal tax due

how do I show that my parents are paying it so they can use it on their return the following year?

Get your taxes done using TurboTax

Federal tax due on anyone's return isn't tax deductible on your federal return, so they don't get the deduction.

However, state tax due IS.  Next year, they can just put the amount (if any) in Estimates and Other Taxes Paid>>Other Income Taxes.

They will need to have a copy of your 2016 state income tax return when they do next year's taxes.