If you purchased a car in 2015, you can only deduct sales tax you paid on your 2015 tax return if you have filed one. Do not include on your 2016 tax return.
If you filed your 2015 taxes with TurboTax, to amend, follow :
2015
Amendment
In the program, as you amend your return, by entering the information under the Federal Tax / Deductions and Credits / Estimated Taxes and Other Taxes Pay / Sales Tax section will flow to the state tax section to calculate your state taxes correctly.
