Deductions shall be made from any child’s insurance benefit to which a child who has attained the age of eighteen is entitled, or from any mother’s or father’s insurance benefit to which a person is entitled, until the total of such deductions equals such child’s insurance benefit or benefits or mother’s or father’s insurance benefit or benefits under section 402 of this title for any month in which such child or person entitled to mother’s or father’s insurance benefits is married to an individual under retirement age (as defined in section 416( l ) of this title) who is entitled to old-age insurance benefits and for more than forty-five hours of which such individual engaged in noncovered remunerative activity outside the United States.