I assume you are aware that sales tax paid on a car is an itemized deduction. You may get a tax benefit if you take the sales tax deduction instead of the state income tax deduction and if your total tax deductions are less than $10,000 before adding the car sales tax and if the total of all your itemized deductions is more than the standard deduction. With the big increases in standard deduction for 2018, it is estimated that a high percentage of taxpayers who itemized in past years will not get a benefit from itemizing on their 2018 tax return.
