Social Security Taxes Estimate how much of your Social Security benefit may be considered taxable. You are viewing this website at a small screen resolution which doesn't support calculators. Click here to view this calculator. Share | Related Content The Facts About Income Tax Millions faithfully file their 1040 forms each April. But some things about federal income taxes may surprise you. How Income Taxes Work A quick look at how federal income taxes work. Federal Income Tax Use this calculator to estimate your income tax liability along with average and marginal tax rates.