§ 424a.
(a)
Conditions for reduction; computation
If for any month prior to the month in which an individual attains retirement age (as defined in section 416(l)(1) of this title)—
(2)
such individual is entitled for such month to—
(A)
periodic benefits on account of his or her total or partial disability (whether or not permanent) under a workmen’s compensation law or plan of the United States or a State, or
(B)
periodic benefits on account of his or her total or partial disability (whether or not permanent) under any other law or plan of the United States, a State, a political subdivision (as that term is used in
section 418(b)(2) of this title), or an instrumentality of two or more States (as that term is used in
section 418(g) of this title), other than (i) benefits payable under title 38, (ii) benefits payable under a program of assistance which is based on need, (iii) benefits based on service all or substantially all of which was included under an agreement entered into by a State and the Commissioner of Social Security under
section 418 of this title, and (iv) benefits under a law or plan of the United States based on service all or substantially all of which is employment as defined in
section 410 of this title,
the total of his benefits under
section 423 of this title for such month and of any benefits under
section 402 of this title for such month based on his wages and self-employment income shall be reduced (but not below zero) by the amount by which the sum of—
(3)
such total of benefits under sections 423 and 402 of this title for such month, and
(4)
such periodic benefits payable (and actually paid) for such month to such individual under such laws or plans,
(5)
80 per centum of his “average current earnings”, or
(6)
the total of such individual’s disability insurance benefits under
section 423 of this title for such month and of any monthly insurance benefits under
section 402 of this title for such month based on his wages and self-employment income, prior to reduction under this section.
In no case shall the reduction in the total of such benefits under sections 423 and 402 of this title for a month (in a continuous period of months) reduce such total below the sum of—
(7)
the total of the benefits under sections 423 and 402 of this title, after reduction under this section, with respect to all persons entitled to benefits on the basis of such individual’s wages and self-employment income for such month which were determined for such individual and such persons for the first month for which reduction under this section was made (or which would have been so determined if all of them had been so entitled in such first month), and
(8)
any increase in such benefits with respect to such individual and such persons, before reduction under this section, which is made effective for months after the first month for which reduction under this section is made.
For purposes of clause (5), an individual’s average current earnings means the largest of (A) the average monthly wage (determined under
section 415(b) of this title as in effect prior to January 1979) used for purposes of computing his benefits under
section 423 of this title, (B) one-sixtieth of the total of his wages and self-employment income (computed without regard to the limitations specified in sections 409(a)(1) and 411(b)(1) of this title) for the five consecutive calendar years after 1950 for which such wages and self-employment income were highest, or (C) one-twelfth of the total of his wages and self-employment income (computed without regard to the limitations specified in sections 409(a)(1) and 411(b)(1) of this title) for the calendar year in which he had the highest such wages and income during the period consisting of the calendar year in which he became disabled (as defined in
section 423(d) of this title) and the five years preceding that year.
([Aug. 14, 1935, ch. 531], title II, § 224, as added [Pub. L. 89–97, title III, § 335], July 30, 1965, [79 Stat. 406]; amended [Pub. L. 90–248, title I, § 159(a)], Jan. 2, 1968, [81 Stat. 869]; [Pub. L. 92–603, title I, § 119(a)], (b), Oct. 30, 1972, [86 Stat. 1352]; [Pub. L. 94–202, § 8(j)], Jan. 2, 1976, [89 Stat. 1140]; [Pub. L. 95–216, title II, § 205(d)], title III, § 353(c), Dec. 20, 1977, [91 Stat. 1529], 1553; [Pub. L. 97–35, title XXII, § 2208(a)], Aug. 13, 1981, [95 Stat. 839]; [Pub. L. 99–272, title XII, § 12109(a)], Apr. 7, 1986, [100 Stat. 286]; [Pub. L. 99–509, title IX, § 9002(c)(2)(F)], Oct. 21, 1986, [100 Stat. 1972]; [Pub. L. 101–239, title X, § 10208(b)(2)(A)], (C), (d)(2)(A)(i), (iii), Dec. 19, 1989, [103 Stat. 2477], 2478, 2480, 2481; [Pub. L. 103–296, title I, § 107(a)(4)], title III, § 321(e)(2)(H), Aug. 15, 1994, [108 Stat. 1478], 1540; [Pub. L. 113–295, div. B, title II, § 201(a)], Dec. 19, 2014, [128 Stat. 4064].)