the credit allowable under subsection (a) shall be reduced (but not below zero) by $100 for each $1,000 (or fraction thereof) by which the taxpayer’s modified adjusted gross income exceeds the threshold amount. (2) Modified adjusted gross income The term modified adjusted gross income means adjusted gross income increased by any amount excluded from gross income under section 911, 931, or 933. (3) Threshold amount The term threshold amount means— (A) $150,000 in the case of a joint return, and (B) $75,000 in any other case. (4) Indexing In the case of any taxable year beginning in a calendar year after 2017, each dollar amount contained in paragraph (3) shall be increased by an amount equal to the product of— (A) such dollar amount, and (B) the cost-of-living adjustment determined under section 1(f)(3) for the calendar year in which the taxable year begins, determined by substituting “calendar year 2016” for “calendar year 1992” in subparagraph (B) thereof. (5) Rounding rule If any increase determined under paragraph (4) is not a multiple of $50, such increase shall be rounded to the next lowest multiple of $50. (g) Identification of Eligible Caregiver with Care Recipient (Qualified care recipient) Identification Requirement No credit shall be allowed under this section to a taxpayer with respect to any qualified care recipient unless the taxpayer includes the name and taxpayer identification number of such individual, and the identification number of the licensed health care practitioner certifying such individual, on the return of tax for the taxable year. . (b) Clerical amendment The table of sections for subpart A of part IV of subchapter A of chapter 1 of such Code is amended by inserting after the item relating to section 25D the following new item: Sec. 25E. Working family caregivers. . (c) Effective date The amendments made by this section shall apply to taxable years beginning after December 31, 2016.