Is there a cap for the state sales tax deduction or is there an artificial cap in Turbo Tax - refund doesn't change when sales tax greater than $40,000 is entered?

[ppm4]

My federal refund does not change when I enter sales tax paid in excess of $40,000.  My understanding is that all WA state sales tax is deductible if I have receipts to prove payment of sales tax.  If so, it seems that the federal refund should increase with increased state sales tax paid.  

[BobinCT]

If you are subject to Alternative Minimum Tax, your deduction for state and local taxes is capped or eliminated altogether.

[CarolC]

There is not a cap on your sales tax deduction.  However, if you make too much money, there may be a phase-out (reduction of) your total itemized deductions based on your adjusted gross income.

Click this TurboTax article Tax Changes You Need to Know for 2017 for more information.