; and (2) the term STEM teacher means a teacher of science, technology, engineering, or mathematics. . 3. Above-the-line-deduction for STEM education materials (a) In general Section 62(a)(2)(D) of the Internal Revenue Code of 1986 is amended by adding at the end the following flush matter: In the case of taxable years beginning after December 31, 2018, the $250 amount in clause (i) shall be increased by an amount equal to so much of the amounts paid or incurred by the eligible educator for STEM education supplies as does not exceed $250. . (b) Inflation adjustment Section 62(d)(3) of such Code is amended to read as follows: (3) Inflation adjustment (A) In general In the case of any taxable year beginning after 2015, the first $250 amount in subsection (a)(2)(D) shall be increased by an amount equal to— (i) such dollar amount, multiplied by (ii) 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 2014 for calendar year 2016 in subparagraph (A)(ii) thereof. (B) STEM education supplies In the case of any taxable year beginning after 2019, the $250 amount in subsection (a)(2)(D) shall be increased by an amount equal to— (i) such dollar amount, multiplied by (ii) 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 2018 for calendar year 2016 in subparagraph (A)(ii) thereof. (C) Rounding Any increase determined under subparagraph (A) or (B) shall be rounded to the nearest multiple of $50. . (c) STEM education supplies defined Section 62(d) of such Code, as amended by subsection (b), is amended by redesignating paragraphs (2) and (3) as paragraphs (3) and (4), respectively, and by inserting after paragraph (1) the following new paragraph: (2) STEM education supplies For purposes of subsection (a)(2)(D), the term STEM education supplies means expenses for books, supplies, equipment, and other materials used