26 U.S.C. § 22: Credit for the elderly and the permanently and totally disabled

In the case of a qualified individual, there shall be allowed as a credit against the tax imposed by this chapter for the taxable year an amount equal to 15 percent of such individual’s section 22 amount for such taxable year. who has attained age 65 before the close of the taxable year, or who retired on disability before the close of the taxable year and who, when he retired, was permanently and totally disabled. An individual’s section 22 amount for the taxable year shall be the applicable initial amount determined under paragraph (2), reduced as provided in paragraph (3) and in subsection (d). $5,000 in the case of a single individual, or a joint return where only one spouse is a qualified individual, $7,500 in the case of a joint return where both spouses are qualified individuals, or $3,750 in the case of a married individual filing a separate return. In the case of a qualified individual who has not attained age 65 before the close of the taxable year, except as provided in clause (ii), the initial amount shall not exceed the disability income for the taxable year. if both spouses have not attained age 65 before the close of the taxable year, the initial amount shall not exceed the sum of such spouses’ disability income, or if one spouse has attained age 65 before the close of the taxable year, the initial amount shall not exceed the sum of $5,000 plus the disability income for the taxable year of the spouse who has not attained age 65 before the close of the taxable year. For purposes of this subparagraph, the term “disability income” means the aggregate amount includable in the gross income of the individual for the taxable year under section 72 or 105(a) to the extent such amount constitutes wages (or payments in lieu of wages) for the period during which the individual is absent from work on account of permanent and total disability. title II of the Social Security Act, the Railroad Retirement Act of 1974, or a law administered by the Department of Veterans Affairs, or which is excluded from gross income under any provision of law not contained in this title. For purposes of subparagraph (A), any amount treated as a social security benefit under section 86(d)(3) shall be treated as a disability benefit received under title II of the Social Security Act. $7,500 in the case of a single individual, $10,000 in the case of a joint return, or $5,000 in the case of a married individual filing a separate return, Except in the case of a husband and wife who live apart at all times during the taxable year, if the taxpayer is married at the close of the taxable year, the credit provided by this section shall be allowed only if the taxpayer and his spouse file a joint return for the taxable year. Marital status shall be determined under section 7703. An individual is permanently and totally disabled if he is unable to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment which can be expected to result in death or which has lasted or can be expected to last for a continuous period of not less than 12 months. An individual shall not be considered to be permanently and totally disabled unless he furnishes proof of the existence thereof in such form and manner, and at such times, as the Secretary may require. No credit shall be allowed under this section to any nonresident alien. The amendments made by this section [amending sections 37 [now 22], 41 [now 24], 44A [now 21], 46, 53, 85, 105, 128, 403, 415, 904, and 7871 of this title] shall apply to taxable years beginning after December 31, 1983 . If an individual’s annuity starting date was deferred under section 105(d)(6) of the Internal Revenue Code of 1986 [formerly I.R.C. 1954] (as in effect on the day before the date of the enactment of this section [ Apr. 20, 1983 ]), such deferral shall end on the first day of such individual’s first taxable year beginning after December 31, 1983 .” The amendments made by paragraphs (1) and (2) [amending this section] shall apply to taxable years beginning after December 31, 1975 . The amendments made by paragraph (3) [amending this section] shall apply to taxable years beginning after December 31, 1977 .”