20 CFR § 218.40 - When a widow(er) annuity ends.
(a) Entitlement based on age. When a widow(er)'s annuity is based on age, the annuity ends with the earliest of the last day of the month before the month in which—
(1) The widow(er) dies;
(2) The widow(er) remarries (the widow(er) may be entitled to benefits as a remarried widow(er) as explained in part 216 of this chapter);
(3) The widow(er) becomes entitled to another survivor annuity in a larger amount, unless he or she elects to be paid the smaller annuity; or
(4) The Board approves an award to someone else as the employee's legal widow(er) if entitlement is based on a deemed valid marriage.
(b) Disabled widow(er). If entitlement is based on the widow(er)'s disability, the annuity ends with the earliest of—
(1) The last day of the month shown in paragraph (a) of this section;
(2) The last day of the second month following the month in which the disability ends; or
(3) The last day of the month before the month in which the widow(er) attains age 60 (the disability annuitant then becomes entitled to an annuity based upon age).
(c) Annuity entitlement based on “child in care.” A widow(er) annuity based on having a “child in care” ends as shown in this paragraph if he or she is not eligible for a widow(er) annuity based on age as explained in part 216 of this chapter. However, see also paragraph (d) of this section. If the widow(er) is eligible for a widow(er) annuity based on age, when he or she is no longer entitled on the basis of having a “child in care,” his or her annuity is changed to a widow(er) annuity based on age. A widow(er) annuity based on having a “child in care” ends with the earliest of—
(1) The last day of the month shown in paragraph (a) of this section;
(2) The last day of the month before the month in which the child is no longer in the widow(er)'s care as explained in part 216 of this chapter (in this case entitlement to the annuity does not terminate, but no annuity is payable while the child is no longer in care);
(3) The last day of the month before the month in which the child attains age 18 and is not disabled;
(4) The last day of the month before the month in which the widow(er) attains full retirement age (the “child in care” annuity is changed to an age annuity);
(5) The last day of the month before the month in which the child marries;
(6) The last day of the month before the month in which the child dies; or
(7) The last day of the second month after the month in which the child's disability ends, if the child is over age 18.
(d) Tier I benefit entitlement based on child in care. The tier I benefit of a widow(er), entitled because he or she has a “child in care” and is not otherwise entitled to a tier I benefit based on age, ends with the earliest of—
(1) The last day of the month shown in paragraph (a) of this section;
(2) The last day of the month before the month in which the child is no longer in the widow(er)'s care as explained in part 216 of this chapter;
(3) The last day of the month before the month in which the child attains age 16 and is not disabled;
(4) The last day of the month before the month in which the child marries;
(5) The last day of the month before the month in which the child dies; or
(6) The last day of the second month after the month in which the child's disability ends, if the child is over age 16.