(A) The term “period of disability” means a continuous period (beginning and ending as hereinafter provided in this subsection) during which an individual was under a disability (as defined in paragraph (1)), but only if such period is of not less than five full calendar months’ duration or such individual was entitled to benefits under section 423 of this title for one or more months in such period.
(B) No period of disability shall begin as to any individual unless such individual files an application for a disability determination with respect to such period; and no such period shall begin as to any individual after such individual attains retirement age (as defined in subsection ( l )). In the case of a deceased individual, the requirement of an application under the preceding sentence may be satisfied by an application for a disability determination filed with respect to such individual within 3 months after the month in which he died.
(C) A period of disability shall begin— (i) on the day the disability began, but only if the individual satisfies the requirements of paragraph (3) on such day; or (ii) if such individual does not satisfy the requirements of paragraph (3) on such day, then on the first day of the first quarter thereafter in which he satisfies such requirements.
(D) A period of disability shall end with the close of whichever of the following months is the earlier: (i) the month preceding the month in which the individual attains retirement age (as defined in subsection ( l )), or (ii) the month preceding (I) the termination month (as defined in section 423(a)(1) of this title ), or, if earlier (II) the first month for which no benefit is payable by reason of section 423(e) of this title , where no benefit is payable for any of the succeeding months during the 36-month period referred to in such section. The provisions set forth in section 423(f) of this title with respect to determinations of whether entitlement to benefits under this subchapter or subchapter XVIII based on the disability of any individual is terminated (on the basis of a finding that the physical or mental impairment on the basis of which such benefits are provided has ceased, does not exist, or is not disabling) shall apply in the same manner and to the same extent with respect to determinations of whether a period of disability has ended (on the basis of a finding that the physical or mental impairment on the basis of which the finding of disability was made has ceased, does not exist, or is not disabling).
(E) Except as is otherwise provided in subparagraph (F), no application for a disability determination which is filed more than 12 months after the month prescribed by subparagraph (D) as the month in which the period of disability ends (determined without regard to subparagraph (B) and this subparagraph) shall be accepted as an application for purposes of this paragraph.
(F) An application for a disability determination which is filed more than 12 months after the month prescribed by subparagraph (D) as the month in which the period of disability ends (determined without regard to subparagraphs (B) and (E)) shall be accepted as an application for purposes of this paragraph if— (i) in the case of an application filed by or on behalf of an individual with respect to a disability which ends after January 1968, such application is filed not more than 36 months after the month in which such disability ended, such individual is alive at the time the application is filed, and the Commissioner of Social Security finds in accordance with regulations prescribed by the Commissioner that the failure of such individual to file an application for a disability determination within the time specified in subparagraph (E) was attributable to a physical or mental condition of such individual which rendered him incapable of executing such an application, and (ii) in the case of an application filed by or on behalf of an individual with respect to a period of disability which ends in or before January 1968— (I) such application is filed not more than 12 months after January 1968, (II) a previous application for a disability determination has been filed by or on behalf of such individual (1) in or before January 1968, and (2) not more than 36 months after the month in which his disability ended, and (III) the Commissioner of Social Security finds in accordance with regulations prescribed by the Commissioner, that the failure of such individual to file an application within the then specified time period was attributable to a physical or mental condition of such individual which rendered him incapable of executing such an application. In making a determination under this subsection, with respect to the disability or period of disability of any individual whose application for a determination thereof is accepted solely by reason of the provisions of this subparagraph (F), the provisions of this subsection (other than the provisions of this subparagraph) shall be applied as such provisions are in effect at the time such determination is made.
(G) An application for a disability determination filed before the first day on which the applicant satisfies the requirements for a period of disability under this subsection shall be deemed a valid application (and shall be deemed to have been filed on such first day) only if the applicant satisfies the requirements for a period of disability before the Commissioner of Social Security makes a final decision on the application and no request under section 405(b) of this title for notice and opportunity for a hearing thereon is made or, if such a request is made, before a decision based upon the evidence adduced at the hearing is made (regardless of whether such decision becomes the final decision of the Commissioner of Social Security).
