May 15, 2017 If You Itemize Deductions, Avoid Tax Surprises with a “Paycheck Checkup” People who’ve itemized deductions on past tax returns should do a “paycheck checkup” using the updated IRS Withholding Estimator. This is especially important due to tax law changes from the Tax Cuts and Jobs Act, such as: A cap on deductions for state and local taxes. Limits to the deduction for home mortgage interest in certain cases. Eliminated deductions for employee business expenses, tax preparation fees and investment expenses. See IRS.gov/taxreform for more information.