The Facts About Income Tax Millions faithfully file their 1040 forms each April. But some things about federal income taxes may surprise you. Share | Related Content Federal Income Tax Use this calculator to estimate your income tax liability along with average and marginal tax rates. How to Appeal Your Property Taxes For homeowners who think their property taxes are too high, there are ways to appeal. Home Mortgage Deduction Use this calculator to assess the potential benefits of a home mortgage deduction.