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 Social Security Taxes Estimate how much of your Social Security benefit may be considered taxable. How to Appeal Your Property Taxes For homeowners who think their property taxes are too high, there are ways to appeal. Comparing Investments This calculator compares the net gain of a taxable investment versus a tax-favored one.