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 Home Mortgage Deduction Use this calculator to assess the potential benefits of a home mortgage deduction. What If You Get Audited? The chances of an IRS audit aren't that high. And being audited does not necessarily imply that the IRS suspects wrongdoing. Federal Income Tax Use this calculator to estimate your income tax liability along with average and marginal tax rates.