1. Short title This Act may be cited as the American Family Act of 2017 . 2. Establishment of fully refundable child tax credit (a) Elimination of existing child tax credit Subpart A of part IV of subchapter A of chapter 1 of subtitle A of the Internal Revenue Code of 1986 is amended by striking section 24. (b) Establishment of fully refundable child tax credit Subpart C of part IV of subchapter A of chapter 1 of subtitle A of such Code is amended by inserting after section 36B the following new section: 36C. Child tax credit (a) Allowance of credit There shall be allowed as a credit against the tax imposed by this chapter for the taxable year an amount equal to the sum of— (1) with respect to each qualifying child of the taxpayer who has attained 6 years of age before the close of such taxable year and for which the taxpayer is allowed a deduction under section 151, an amount equal to $3,000, and (2) with respect to each qualifying child of the taxpayer who has not attained 6 years of age before the close of such taxable year and for which the taxpayer is allowed a deduction under section 151, an amount equal to 120 percent of the dollar amount in paragraph (1). (b) Limitation (1) In general The amount of the credit allowable under subsection (a) shall be reduced (but not below zero) by the applicable amount for each $1,000 (or fraction thereof) by which the taxpayer's modified adjusted gross income exceeds the threshold amount. For purposes of the preceding sentence, the term modified adjusted gross income means adjusted gross income increased by any amount excluded from gross income under section 911, 931, or 933. (2) Threshold amount (A) In general For purposes of paragraph (1), the term threshold amount means— (i) $110,000 in the case of a joint return, (ii) $75,000 in the case of an individual who is not married, and (iii) $55,000 in the case of a married individual filing a separate return. (B) Marital status For purposes of this paragraph, marital status shall be determined under section 7703. (3)