In December of 2015, President Obama signed an omnibus tax and spending package (Consolidated Appropriations Act, 2016) that includes a permanent extension of the federal sales tax deduction for Washington residents. As a result, Washington State residents may deduct state and local general-sales tax on their federal income returns for tax year 2015 and succeeding tax years.
The deduction is available to taxpayers that itemize deductions, not those who take the standard deduction. The deduction is based on adjusted gross income and number of exemptions claimed. Taxpayers who keep all their receipts can deduct actual sales tax and use tax paid. For taxpayers who didn't keep receipts, the IRS has an online Sales Tax Deduction Calculator to determine the amount of optional general sales tax to claim, or taxpayers can use the Optional State Sales Tax Tables.