; and (2) by striking 7.65 in the third column of the fourth row and inserting 15.3 . (c) Credit allowed for certain childless individuals over age 21 Subclause (II) of section 32(c)(1)(A)(ii) of the Internal Revenue Code of 1986 is amended by striking age 25 and inserting age 21 . (d) Effective dates The amendments made by this section shall apply to taxable years beginning after December 31, 2016. 3. Strengthening the child tax credit (a) Increase in amount of credit for taxpayers with young children Subsection (a) of section 24 of the Internal Revenue Code of 1986 is amended to read as follows: (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 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 $3,000, and (2) 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 $1,000. . (b) Increase in portion of credit refundable for taxpayers with young children Clause (i) of section 24(d)(1)(B) of the Internal Revenue Code of 1986 is amended to read as follows: (i) (I) in the case of a taxpayer with a qualifying child who has not attained 6 years of age before the close of the taxable year, 45 percent of so much of the taxpayer's earned income (within the meaning of section 32) which is taken into account in computing taxable income for the taxable year, or (II) in the case of a taxpayer not described in subclause (I), 15 percent of so much of the taxpayer's earned income (within the meaning of section 32) which is taken into account in computing taxable income for the taxable year as exceeds $3,000, or . (c) Effective date The amendments made by this section shall apply to taxable years beginning