20 CFR § 228.15
Reduction for age
February 18, 2021
(a) Widow(er), surviving divorced spouse, or remarried widow(er). The tier I annuity component is reduced 19⁄40 of 1 percent multiplied by the number of months before the annuitant attains full retirement age (presently age 65) effective with the annuity beginning date for widow(ers) born before 1/2/40. (For widow(ers) born after 1/1/40, see section 216(l) of the Social Security Act.)
(b) Disabled widow(er), disabled surviving divorced spouse, or disabled remarried widow(er). The tier I annuity component is reduced for a maximum of 60 months even though the annuity may begin at age 50.