Reg. § 1.59A-10 Applicability date.
(a) General applicability date Sections through 1.59A-9, other than the provisions described in the first sentence of of this section or in of this section, apply to taxable years ending on or after December 17, 2018. However, taxpayers may apply the regulations in this in their entirety for taxable years beginning after December 31, 2017, and ending before December 17, 2018. In lieu of applying the regulations referred to in the first sentence of this , taxpayers may apply the provisions matching through -9 from the Internal Revenue Bulletin (IRB) 2019-02 (https:www.irs.gov/irb2019-02_IRB) in their entirety for all taxable years beginning after December 31, 2017, and ending on or before December 6, 2019.
(b) Exception Sections and (c)(4) through (6), 1.59A-3(b)(3)(iii)(C), 1.59A-3(c)(5) and (6), and 1.59A-9(b)(4) apply to taxable years beginning on or after October 9, 2020, and and and apply to taxable years ending on or after December 2, 2019. Taxpayers may apply those regulations in their entirety for taxable years beginning after December 31, 2017, and before their applicability date, provided that, once applied, taxpayers must continue to apply them in their entirety for all subsequent taxable years. Alternatively, taxpayers may apply only and for taxable years beginning after December 31, 2017, and before their applicability date, provided that, once applied, taxpayers must continue to apply and in their entirety for all subsequent taxable years.
(c) Additional applicability dates for certain rules relating to securities lending transactions Sections and 1.59A-6(b)(3)(iii) and (iv) apply to taxable years beginning on or after December 17, 2025.
[T.D. 9910, 85 FR 64368, Oct. 9, 2020, as amended by T.D. 10041, 90 FR 59051, Dec. 18, 2025]