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.