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 Comparing Investments This calculator compares the net gain of a taxable investment versus a tax-favored one. Does Your Child Need to File an Income Tax Return? When your child has income, there’s a good chance that he or she will need to report it and pay taxes. Tax Freedom Day Assess how many days you'll work to pay your federal tax liability.