1. Short title This Act may be cited as the Paying a Fair Share Act of 2017 . 2. Fair share tax on high-income taxpayers (a) In general Subchapter A of chapter 1 of the Internal Revenue Code of 1986 is amended by adding at the end the following new part: VII Fair share tax on high-income taxpayers Sec. 59A. Fair share tax. 59A. Fair share tax (a) General rule (1) Phase-in of tax In the case of any high-income taxpayer, there is hereby imposed for a taxable year (in addition to any other tax imposed by this subtitle) a tax equal to the product of— (A) the amount determined under paragraph (2), and (B) a fraction (not to exceed 1)— (i) the numerator of which is the excess of— (I) the taxpayer's adjusted gross income, over (II) the dollar amount in effect under subsection (c)(1), and (ii) the denominator of which is the dollar amount in effect under subsection (c)(1). (2) Amount of tax The amount of tax determined under this paragraph is an amount equal to the excess (if any) of— (A) the tentative fair share tax for the taxable year, over (B) the excess of— (i) the sum of— (I) the regular tax liability (as defined in section 26(b)) for the taxable year, determined without regard to any tax liability determined under this section, (II) the tax imposed by section 55 for the taxable year, plus (III) the payroll tax for the taxable year, over (ii) the credits allowable under part IV of subchapter A (other than sections 27(a), 31, and 34). (b) Tentative fair share tax For purposes of this section— (1) In general The tentative fair share tax for the taxable year is 30 percent of the excess of— (A) the adjusted gross income of the taxpayer, over (B) the modified charitable contribution deduction for the taxable year. (2) Modified charitable contribution deduction For purposes of paragraph (1)— (A) In general The modified charitable contribution deduction for any taxable year is an amount equal to the amount which bears the same ratio to the deduction allowable under section 170 (section 642(c) in the case of a trust or