5 U.S.C. § 8444: Rights of a named individual with an insurable interest

The annuity of a survivor named under section 8420(a) is 55 percent of the reduced annuity of the retired employee or Member determined under paragraph (2) of such section 8420(a). The annuity of the survivor commences on the day after the retired employee or Member dies. This annuity and the right thereto terminate on the last day of the month before the survivor dies.