((a)) ** In general**
((1)) ** In general** Except as provided in paragraph (2), gross income for the taxable year of any taxpayer described in subsection (b) (notwithstanding section 207 of the Social Security Act) includes social security benefits in an amount equal to the lesser of—
((A)) one-half of the social security benefits received during the taxable year, or
((B)) one-half of the excess described in subsection (b)(1).
((2)) ** Additional amount** In the case of a taxpayer with respect to whom the amount determined under subsection (b)(1)(A) exceeds the adjusted base amount, the amount included in gross income under this section shall be equal to the lesser of—
((A)) the sum of—
((i)) 85 percent of such excess, plus
((ii)) the lesser of the amount determined under paragraph (1) or an amount equal to one-half of the difference between the adjusted base amount and the base amount of the taxpayer, or
((B)) 85 percent of the social security benefits received during the taxable year.
((b)) ** Taxpayers to whom subsection (a) applies**
((1)) ** In general** A taxpayer is described in this subsection if—
((A)) the sum of—
((i)) the modified adjusted gross income of the taxpayer for the taxable year, plus
((ii)) one-half of the social security benefits received during the taxable year, exceeds
((B)) the base amount.
((2)) ** Modified adjusted gross income** For purposes of this subsection, the term “modified adjusted gross income” means adjusted gross income—
((A)) determined without regard to this section and sections 85(c), 135, 137, 221, 911, 931, and 933, and
((B)) increased by the amount of interest received or accrued by the taxpayer during the taxable year which is exempt from tax.
((c)) ** Base amount and adjusted base amount** For purposes of this section—
((1)) ** Base amount** The term “base amount” means—
((A)) except as otherwise provided in this paragraph, $25,000,
((B)) $32,000 in the case of a joint return, and
((C)) zero in the case of a taxpayer who—
((i)) is married as of the close of the taxable year (within the meaning of section 7703) but does not file a joint return for such year, and
((ii)) does not live apart from his spouse at all times during the taxable year.
((2)) ** Adjusted base amount** The term “adjusted base amount” means—
((A)) except as otherwise provided in this paragraph, $34,000,
((B)) $44,000 in the case of a joint return, and
((C)) zero in the case of a taxpayer described in paragraph (1)(C).
((d)) ** Social security benefit**
((1)) ** In general** For purposes of this section, the term “social security benefit” means any amount received by the taxpayer by reason of entitlement to—
((A)) a monthly benefit under title II of the Social Security Act, or
((B)) a tier 1 railroad retirement benefit.
((2)) ** Adjustment for repayments during year**
((A)) ** In general** For purposes of this section, the amount of social security benefits received during any taxable year shall be reduced by any repayment made by the taxpayer during the taxable year of a social security benefit previously received by the taxpayer (whether or not such benefit was received during the taxable year).
((B)) ** Denial of deduction** If (but for this subparagraph) any portion of the repayments referred to in subparagraph (A) would have been allowable as a deduction for the taxable year under section 165, such portion shall be allowable as a deduction only to the extent it exceeds the social security benefits received by the taxpayer during the taxable year (and not repaid during such taxable year).
((3)) ** Workmen’s compensation benefits substituted for social security benefits** For purposes of this section, if, by reason of section 224 of the Social Security Act (or by reason of section 3(a)(1) of the Railroad Retirement Act of 1974), any social security benefit is reduced by reason of the receipt of a benefit under a workmen’s compensation act, the term “social security benefit” includes that portion of such benefit received under the workmen’s compensation act which equals such reduction.
((4)) ** Tier 1 railroad retirement benefit** For purposes of paragraph (1), the term “tier 1 railroad retirement benefit” means—
((A)) the amount of the annuity under the Railroad Retirement Act of 1974 equal to the amount of the benefit to which the taxpayer would have been entitled under the Social Security Act if all of the service after , of the employee (on whose employment record the annuity is being paid) had been included in the term “employment” as defined in the Social Security Act, and
((B)) a monthly annuity amount under section 3(f)(3) of the Railroad Retirement Act of 1974.
((5)) ** Effect of early delivery of benefit checks** For purposes of subsection (a), in any case where section 708 of the Social Security Act causes social security benefit checks to be delivered before the end of the calendar month for which they are issued, the benefits involved shall be deemed to have been received in the succeeding calendar month.
((e)) ** Limitation on amount included where taxpayer receives lump-sum payment**
((1)) ** Limitation** If—
((A)) any portion of a lump-sum payment of social security benefits received during the taxable year is attributable to prior taxable years, and
((B)) the taxpayer makes an election under this subsection for the taxable year,
((2)) ** Special rules**
((A)) ** Year to which benefit attributable** For purposes of this subsection, a social security benefit is attributable to a taxable year if the generally applicable payment date for such benefit occurred during such taxable year.
((B)) ** Election** An election under this subsection shall be made at such time and in such manner as the Secretary shall by regulations prescribe. Such election, once made, may be revoked only with the consent of the Secretary.
((f)) ** Treatment as pension or annuity for certain purposes** For purposes of—
((1)) section 22(c)(3)(A) (relating to reduction for amounts received as pension or annuity),
((2)) section 32(c)(2) (defining earned income),
((3)) section 219(f)(1) (defining compensation), and
((4)) section 911(b)(1) (defining foreign earned income),
