computation base years
(2) (A) The number of an individual’s benefit computation years equals the number of elapsed years reduced— (i) in the case of an individual who is entitled to old-age insurance benefits (except as provided in the second sentence of this subparagraph), or who has died, by 5 years, and (ii) in the case of an individual who is entitled to disability insurance benefits, by the number of years equal to one-fifth of such individual’s elapsed years (disregarding any resulting fractional part of a year), but not by more than 5 years. Clause (ii), once applicable with respect to any individual, shall continue to apply for purposes of determining such individual’s primary insurance amount for purposes of any subsequent eligibility for disability or old-age insurance benefits unless prior to the month in which such eligibility begins there occurs a period of at least 12 consecutive months for which he was not entitled to a disability or an old-age insurance benefit. If an individual described in clause (ii) is living with a child (of such individual or his or her spouse) under the age of 3 in any calendar year which is included in such individual’s computation base years, but which is not disregarded pursuant to clause (ii) or to subparagraph (B) (in determining such individual’s benefit computation years) by reason of the reduction in the number of such individual’s elapsed years under clause (ii), the number by which such elapsed years are reduced under this subparagraph pursuant to clause (ii) shall be increased by one (up to a combined total not exceeding 3) for each such calendar year; except that (I) no calendar year shall be disregarded by reason of this sentence (in determining such individual’s benefit computation years) unless the individual was living with such child substantially throughout the period in which the child was alive and under the age of 3 in such year and the individual had no earnings as described in section 403(f)(5) of this title in such year, (II) the particular calendar years to be disregarded under this sentence (in determining such benefit computation years) shall be those years (not otherwise disregarded under clause (ii)) which, before the application of subsection (f), meet the conditions of subclause (I), and (III) this sentence shall apply only to the extent that its application would not result in a lower primary insurance amount. The number of an individual’s benefit computation years as determined under this subparagraph shall in no case be less than 2. (B) For purposes of this subsection with respect to any individual— (i) the term “benefit computation years” means those computation base years, equal in number to the number determined under subparagraph (A), for which the total of such individual’s wages and self-employment income, after adjustment under paragraph (3), is the largest; (ii) the term “computation base years” means the calendar years after 1950 and before— (I) in the case of an individual entitled to old-age insurance benefits, the year in which occurred (whether by reason of section 402(j)(1) of this title or otherwise) the first month of that entitlement; or (II) in the case of an individual who has died (without having become entitled to old-age insurance benefits), the year succeeding the year of his death; except that such term excludes any calendar year entirely included in a period of disability; and (iii) the term “number of elapsed years” means (except as otherwise provided by section 104(j)(2) of the Social Security Amendments of 1972) the number of calendar years after 1950 (or, if later, the year in which the individual attained age 21) and before the year in which the individual died, or, if it occurred earlier (but after 1960), the year in which he attained age 62; except that such term excludes any calendar year any part of which is included in a period of disability.