20 C.F.R. § 216.66 Who is an employee's surviving divorced spouse.
Title 20 - Employees' Benefits
An individual who was married to the employee is the deceased employee's surviving divorced spouse if he or she: (a) Was married to the employee for a period of at least 10 years immediately before the date the divorce became final, and applies for an annuity based on age or disability; or (b) Applies for an annuity based on having a “child in care” and either: (1) Is the natural parent of the employee's child; (2) Was married to the employee at the time the employee or the surviving divorced spouse adopted the other's child who was then under 18 years old; or (3) Was married to the employee at the time they adopted a child who was then under 18 years old.
Title 20: Employees' Benefits
PART 216—ELIGIBILITY FOR AN ANNUITY
Subpart G—Widow(er), Surviving Divorced Spouse, and Remarried Widow(er) Annuities
§ 216.66 Who is an employee's surviving divorced spouse.

