20 CFR § 404.132 - How we determine fully insured status for a period of disability or disability insurance benefits.
In determining if you are fully insured for purposes of paragraph (b), (c), (d), or (e) of § 404.130 on disability insured status, we use the fully insured status requirements in § 404.110, but apply the following rules in determining when the period of elapsed years ends:
(a) If you are a woman, or a man born after January 1, 1913, the period of elapsed years in § 404.110(b) used in determining the number of quarters of coverage (QCs) you need to be fully insured ends as of the earlier of—
(2) The year in which—
(i) Your period of disability begins;
(1) The year 1975; or
(2) The year specified in paragraph (a)(2) of this section.