20 CFR 225.36: Effect of DRC's on survivor annuities.

(a) Widow(er), remarried widow(er) or surviving divorced spouse. Delayed retirement credits that the employee earned are used in computing the tier I component of a widow(er), remarried widow(er) or surviving divorced spouse annuity. All DRC's, including credits earned in the year of death, can be used in computing the widow(er) or surviving divorced spouse annuity beginning with the month of death. Delayed retirement credits for months up to, but not including, the month of death are used.

(b) Other survivor annuities. Delayed retirement credits cannot be used in computing any other survivor annuity based on the deceased employee's record.