20 C.F.R. § 230.1
No annuity shall be paid with respect to any month in which an individual in receipt of any annuity hereunder shall render compensated service to an employer or to the last person by whom he was employed prior to the date on which the annuity began to accrue. Individuals receiving annuities shall report to the Board immediately all such compensated service. No annuity under paragraph 4 or 5 of subsection (a) of this section shall be paid to an individual with respect to any month in which the individual is under age sixty-five and is paid more than $100 in earnings from employment or self-employment of any form: Provided, That for purposes of this paragraph, if a payment in any one calendar month is for accruals in more than one calendar month, such payment shall be deemed to have been paid in each of the months in which accrued to the extent accrued in such month. Any such individual under the age of sixty-five shall report to the Board any such payment of earnings for such employment or self-employment before receipt and acceptance of an annuity for the second month following the month of such payment. A deduction shall be imposed, with respect to any such individual who fails to make such report, in the annuity or annuities otherwise due the individual, in an amount equal to the amount of the annuity for each month in which he is paid such earnings in such employment or self-employment, except that the first deduction imposed pursuant to this sentence shall in no case exceed an amount equal to the amount of the annuity otherwise due for the first month with respect to which the deduction is imposed. If pursuant to the third sentence of this subsection an annuity was not paid to an individual with respect to one or more months in any calendar year, and it is subsequently established that the total amount of such individual's earnings during such year as determined in accordance with that sentence (but exclusive of earnings for services described in the first sentence of this subsection) did not exceed $1,200, the annuity with respect to such month or months, and any deduction imposed by reason of the failure to report earnings for such month or months under the fifth sentence of this subsection, shall then be payable. If the total amount of such individual's earnings during such year (exclusive of earnings for services described in the first sentence of this subsection) is in excess of $1,200, the number of months in such year with respect to which an annuity is not payable by reason of such third and fifth sentences shall not exceed one month for each $100 of such excess, treating the last $50 or more of such excess as $100; and if the amount of the annuity has changed during such year, any payments of annuity which become payable solely by reason of the limitation contained in this sentence shall be made first with respect to the month or months for which the annuity is larger. (Section 2(d) of the act.)
20 C.F.R. § 230.1