20 CFR 404.441: Partial monthly benefits; insured individual and another person entitled (or deemed entitled) on the same earnings record both have excess earnings.

Where both the insured individual and another person entitled (or deemed entitled) on the same earnings record have excess earnings (as described in § 404.430), their excess earnings are charged, and their partial monthly benefit is apportioned, as follows:

Example:

M and his wife are initially entitled to combined total benefits of $264 per month based on M's old-age insurance benefit of $176. For the taxable year in question, M's excess earnings were $1,599 and his wife's excess earnings were $265. Both were under age 65. M had wages of more than $340 in all months of the year except February, while his wife had wages of more than $340 in all months of the year. After M's excess earnings have been charged to the appropriate months (all months through July except February), there remains a partial benefit payment for August of $249, which is allocated to M and his wife in the ratio that the original benefit of each bears to the sum of their original benefits: $166 and $83. His wife's excess earnings are charged against her full benefit for February ($88), her partial benefit for August ($83), her full benefit for September, and from $6 of her October benefit, leaving an $82 benefit payable to her for that month.