For purposes of paragraph (1) and subsection (h), an individual’s excess earnings for a taxable year shall be 33⅓ percent of his earnings for such year in excess of the product of the applicable exempt amount as determined under paragraph (8) in the case of an individual who has attained (or, but for the individual’s death, would have attained) retirement age (as defined in section 416( l ) of this title) before the close of such taxable year, or 50 percent of his earnings for such year in excess of such product in the case of any other individual, multiplied by the number of months in such year, except that, in determining an individual’s excess earnings for the taxable year in which he attains retirement age (as defined in section 416( l ) of this title), there shall be excluded any earnings of such individual for the month in which he attains such age and any subsequent month (with any net earnings or net loss from self-employment in such year being prorated in an equitable manner under regulations of the Commissioner of Social Security). For purposes of the preceding sentence, notwithstanding section 411(e) of this title , the number of months in the taxable year in which an individual dies shall be 12. The excess earnings as derived under the first sentence of this paragraph, if not a multiple of $1, shall be reduced to the next lower multiple of $1.