60 STAT.] 79TEH ONG. , 21 SESS.-CH. 957-AUG. 13, 1946 shall in no case exceed 25 per centum of his average basic salary for the five years next preceding his retirement or 662/3 per centum of his reduced annuity. If the age of the participant is less than the age of the wife or exceeds her age by not more than eight years, the annuity of the participant will be reduced by an amount equal to one-half of the annuity which he elects to have paid to his widow. If the age of the participant exceeds the age of the wife by more than eight years, the annuity of the participant will be reduced by an amount equal to one-half the annuity which he elects to have paid to his widow plus an additional reduction equal to 2 per centum of such widow's annuity for each year, or fraction thereof, that the difference in age exceeds eight. The participant may at his option also elect to have his annuity reduced by an additional 5 per centum of the amount which he elects to have paid to his widow, with a provision that, from and after the death of his wife, if the par- ticipant shall survive her, the annuity payable to the participant shall be that amount which would have been payable if no option had been elected. (c) A participant who is not married at the time of his retirement or who is married to a wife who is not entitled to an annuity in accord- ance with the provisions of paragraph (b) of this section may elect to receive a reduced annuity for himself and to provide for an additional annuity payable after his death to a beneficiary whose name shall be notified in writing to the Secretary at the time of his retirement and who is acceptable to the Secretary. The annuity payments payable to such beneficiary shall be either equal to the deceased participant's reduced annuity payments or equal to 50 per centum of such reduced annuity payments and upon the death of the surviving beneficiary all payments shall cease and no further annuity payments shall be due or payable. The combined actuarial value of the two annuities on the date of retirement as determined by the Secretary of the Treasury shall be the same as the actuarial value of the annuity provided by paragraph (a) of this section. No such election of a reduced annuity payable to a beneficiary other than a child of the participant shall be valid until the participant shall have satisfactorily passed a physical examination as prescribed by the Secretary. Annuity payments pay- able in accordance with the provisions of this section to a beneficiary who is a child of a participant shall cease when the beneficiary reaches the age of twenty-one years. PART D--BENEFITS ACCRUING TO CERTAIN PARTICIPANTS BEIIREMENT FOR DISABILITY OR INCAPACITY-PHYSICAL EXAMINATION- RECOVERY SEc. 831. (a) Any participant who, after serving for a total period of not less than five years, becomes totally disabled or incapacitated for useful and efficient service by reason of disease or injury incurred in the line of duty but not due to vicious habits, intemperance, or will- ful misconduct on his part, shall, upon his own application or upon order of the Secretary, be retired on an annuity computed as pre- scribed in section 821. If the disabled or incapacitated participant has had less than twenty years of service at the time he is retired, his annuity shall be computed on the assumption that he had had twenty years of service. (b) In each case such disability shall be determined by the report of a duly qualified physician or surgeon, designated by the Secretary to conduct the examination. Unless the disability is permanent, a like examination shall be made annually until the annuitant has reached the retirement age as defined in sections 631 and 632, and the payment 1021 Survivorship pro- vision. Unmarried partici- pant, etc. Annuity payable to beneficiary. Physical examina- tion. Termination of pay- ments to child bene- ficiary. Total disability. Ante, p. 2 Examination. Alti, p. m0.