2020 . (b) Effective date The amendment made by this section shall apply on and after the first day of the first calendar month beginning after the date of the enactment of this Act. B Incentives for Employment, Economic Growth, and Community Development 111. Indian employment credit (a) In general Section 45A(f) is amended by striking December 31, 2017 and inserting December 31, 2020 . (b) Effective date The amendment made by this section shall apply to taxable years beginning after December 31, 2017. 112. Railroad track maintenance credit (a) In general Section 45G(f) is amended by striking January 1, 2018 and inserting January 1, 2021 . (b) Safe harbor assignments Any assignment, including related expenditures paid or incurred, under section 45G(b)(2) of the Internal Revenue Code of 1986 for a taxable year beginning on or after January 1, 2018, and before January 1, 2019, shall be treated as effective as of the close of such taxable year if made pursuant to a written agreement entered into no later than 90 days following the date of the enactment of this Act. (c) Effective date The amendment made by this section shall apply to expenditures paid or incurred during taxable years beginning after December 31, 2017. 113. Mine rescue team training credit (a) In general Section 45N(e) is amended by striking December 31, 2017 and inserting December 31, 2020 . (b) Effective date The amendment made by this section shall apply to taxable years beginning after December 31, 2017. 114. 7-year recovery period for motorsports entertainment complexes (a) In general Section 168(i)(15)(D) is amended by striking December 31, 2017 and inserting December 31, 2020 . (b) Effective date The amendment made by this section shall apply to property placed in service after December 31, 2017. 115. Accelerated depreciation for business property on Indian reservations (a) In general Section 168(j)(9) is amended by striking December 31, 2017 and inserting December 31, 2020 . (b) Effective date The amendment made by this section shall apply to