20 CFR 404.333 : Employees' Benefits (§ 1.1 To Parts 1011-1099) — (Part 400 To Part 499) — Social Security Administration (Part 400 To Part 499) — Federal Old-Age, Survivors And Disability Insurance (1950- ) (§ 404.1 To § 404.2127) — Old-Age, Disability, Dependents' And Survivors' Insurance Benefits; Period Of Disability (§ 404.301 To § 404.392) — Benefits For Spouses And Divorced Spouses (§ 404.330 To § 404.349) — Wife's and husband's benefit amounts.

Your wife's or husband's monthly benefit is equal to one-half the insured person's primary insurance amount. If you are entitled as a divorced wife or as a divorced husband before the insured person becomes entitled, we will compute the primary insurance amount as if he or she became entitled to old-age benefits in the first month you are entitled as a divorced wife or as a divorced husband. The amount of your monthly benefit may change as explained in § 404.304.