20 CFR § 404.407 - Reduction because of entitlement to other benefits.
(a) Entitlement to old-age or disability insurance benefit and other monthly benefit. If an individual is entitled to an old-age insurance benefit or disability insurance benefit for any month after August 1958 and to any other monthly benefit payable under the provisions of title II of the Act (see subpart D of this part) for the same month, such other benefit for the month, after any reduction under section 202(q) of the Act because of entitlement to such benefit for months before retirement age and any reduction under section 203(a) of the Act, is reduced (but not below zero) by an amount equal to such old-age insurance benefit (after reduction under section 202(q) of the Act) or such disability insurance benefit, as the case may be.
(b) Entitlement to widow's or widower's benefit and other monthly benefit. If an individual is entitled for any month after August 1965 to a widow's or widower's insurance benefit under the provisions of section 202 (e)(4) or (f)(5) of the Act and to any other monthly benefit payable under the provisions of title II of the Act (see subpart D) for the same month, except an old-age insurance benefit, such other insurance benefit for that month, after any reduction under paragraph (a) of this section, any reduction for age under section 202(q) of the Act, and any reduction under the provisions described in section 203(a) of the Act, shall be reduced, but not below zero, by an amount equal to such widow's or widower's insurance benefit after any reduction or reductions under paragraph (a) of this section or section 203(a) of the Act.
(c) Entitlement to old-age insurance benefit and disability insurance benefit. Any individual who is entitled for any month after August 1965 to both an old-age insurance benefit and a disability insurance benefit shall be entitled to only the larger of such benefits for such month, except that where the individual so elects, he or she shall instead be entitled to only the smaller of such benefits for such month. Only a person defined in § 404.612 (a), (c), or (d) may make the above described election.
(d) Child's insurance benefits. A child may, for any month, be simultaneously entitled to a child's insurance benefit on more than one individual's earnings if all the conditions for entitlement described in § 404.350 are met with respect to each claim. Where a child is simultaneously entitled to child's insurance benefits on more than one earnings record, the general rule is that the child will be paid an amount which is based on the record having the highest primary insurance amount. However, the child will be paid a higher amount which is based on the earnings record having a lower primary insurance amount if no other beneficiary entitled on any record would receive a lower benefit because the child is paid on the record with the lower primary insurance amount. (See § 404.353(b).)
(e) Entitlement to more than one benefit where not all benefits are child's insurance benefits and no benefit is an old-age or disability insurance benefit. If an individual (other than an individual to whom section 202 (e)(4) or (f)(5) of the Act applies) is entitled for any month to more than one monthly benefit payable under the provisions of this subpart, none of which is an old-age or disability insurance benefit and all of which are not child's insurance benefits, only the greater of the monthly benefits to which he would (but for the provisions of this paragraph) otherwise be entitled is payable for such month. For months after August 1965, an individual who is entitled for any month to more than one widow's or widower's insurance benefit to which section 202 (e)(4) or (f)(5) of the Act applies is entitled to only one such benefit for such month, such benefit to be the largest of such benefits.