(A) The term “quarter of coverage” means— (i) for calendar years before 1978, and subject to the provisions of subparagraph (B), a quarter in which an individual has been paid $50 or more in wages (except wages for agricultural labor paid after 1954) or for which he has been credited (as determined under section 412 of this title ) with $100 or more of self-employment income; and (ii) for calendar years after 1977, and subject to the provisions of subparagraph (B), each portion of the total of the wages paid and the self-employment income credited (pursuant to section 412 of this title ) to an individual in a calendar year which equals the amount required for a quarter of coverage in that calendar year (as determined under subsection (d)), with such quarter of coverage being assigned to a specific calendar quarter in such calendar year only if necessary in the case of any individual who has attained age 62 or died or is under a disability and the requirements for insured status in subsection (a) or (b) of section 414 of this title , the requirements for entitlement to a computation or recomputation of his primary insurance amount, or the requirements of paragraph (3) of section 416(i) of this title would not otherwise be met.

(B) Notwithstanding the provisions of subparagraph (A)— (i) no quarter after the quarter in which an individual dies shall be a quarter of coverage, and no quarter any part of which is included in a period of disability (other than the initial quarter and the last quarter of such period) shall be a quarter of coverage; (ii) if the wages paid to an individual in any calendar year equal $3,000 in the case of a calendar year before 1951, or $3,600 in the case of a calendar year after 1950 and before 1955, or $4,200 in the case of a calendar year after 1954 and before 1959, or $4,800 in the case of a calendar year after 1958 and before 1966, or $6,600 in the case of a calendar year after 1965 and before 1968, or $7,800 in the case of a calendar year after 1967 and before 1972, or $9,000 in the case of the calendar year 1972, or $10,800 in the case of the calendar year 1973, or $13,200 in the case of the calendar year 1974, or an amount equal to the contribution and benefit base (as determined under section 430 of this title ) in the case of any calendar year after 1974 and before 1978 with respect to which such contribution and benefit base is effective, each quarter of such year shall (subject to clauses (i) and (v)) be a quarter of coverage; (iii) if an individual has self-employment income for a taxable year, and if the sum of such income and the wages paid to him during such year equals $3,600 in the case of a taxable year beginning after 1950 and ending before 1955, or $4,200 in the case of a taxable year ending after 1954 and before 1959, or $4,800 in the case of a taxable year ending after 1958 and before 1966, or $6,600 in the case of a taxable year ending after 1965 and before 1968, or $7,800 in the case of a taxable year ending after 1967 and before 1972, or $9,000 in the case of a taxable year beginning after 1971 and before 1973, or $10,800 in the case of a taxable year beginning after 1972 and before 1974, or $13,200 in the case of a taxable year beginning after 1973 and before 1975, or an amount equal to the contribution and benefit base (as determined under section 430 of this title ) which is effective for the calendar year in the case of any taxable year beginning in any calendar year after 1974 and before 1978, each quarter any part of which falls in such year shall (subject to clauses (i) and (v)) be a quarter of coverage; (iv) if an individual is paid wages for agricultural labor in a calendar year after 1954 and before 1978, then, subject to clauses (i) and (v), (I) the last quarter of such year which can be but is not otherwise a quarter of coverage shall be a quarter of coverage if such wages equal or exceed $100 but are less than $200; (II) the last two quarters of such year which can be but are not otherwise quarters of coverage shall be quarters of coverage if such wages equal or exceed $200 but are less than $300; (III) the last three quarters of such year which can be but are not otherwise quarters of coverage shall be quarters of coverage if such wages equal or exceed $300 but are less than $400; and (IV) each quarter of such year which is not otherwise a quarter of coverage shall be a quarter of coverage if such wages are $400 or more; (v) no quarter shall be counted as a quarter of coverage prior to the beginning of such quarter; (vi) not more than one quarter of coverage may be credited to a calendar quarter; and (vii) no more than four quarters of coverage may be credited to any calendar year after 1977. If in the case of an individual who has attained age 62 or died or is under a disability and who has been paid wages for agricultural labor in a calendar year after 1954 and before 1978, the requirements for insured status in subsection (a) or (b) of section 414 of this title , the requirements for entitlement to a computation or recomputation of his primary insurance amount, or the requirements of paragraph (3) of section 416(i) of this title are not met after assignment of quarters of coverage to quarters in such year as provided in clause (iv) of the preceding sentence, but would be met if such quarters of coverage were assigned to different quarters in such year, then such quarters of coverage shall instead be assigned, for purposes only of determining compliance with such requirements, to such different quarters. If, in the case of an individual who did not die prior to January 1, 1955 , and who attained age 62 (if a woman) or age 65 (if a man) or died before July 1, 1957 , the requirements for insured status in section 414(a)(3) of this title are not met because of his having too few quarters of coverage but would be met if his quarters of coverage in the first calendar year in which he had any covered employment had been determined on the basis of the period during which wages were earned rather than on the basis of the period during which wages were paid (any such wages paid that are reallocated on an earned basis shall not be used in determining quarters of coverage for subsequent calendar years), then upon application filed by the individual or his survivors and satisfactory proof of his record of wages earned being furnished by such individual or his survivors, the quarters of coverage in such calendar year may be determined on the basis of the periods during which wages were earned.