Seniors' Tax Simplification Act of 2017 This bill directs the Internal Revenue Service to make available to taxpayers who have turned age 65 at the close of the taxable year a new federal income tax Form 1040SR (similar to the existing Form 1040EZ). Such taxpayers can use this new form even if their income includes: (1) Social Security benefits; (2) distributions from qualified retirement plans, annuities, or other such deferred payment arrangements; (3) interest and dividends; or (4) capital gains and losses. The form must be available without regard to the amount of any item of taxable income or the total amount of taxable income for the taxable year.