20 CFR 216.68: Disability period for widow(er), surviving divorced spouse, or remarried widow(er).

A widow(er), surviving divorced spouse, or remarried widow(er) who has a disability as defined in part 220 of this chapter is eligible for an annuity only if the disability began before the end of a period which:

(a) Begins in the later of:

(1) The month in which the employee died;

(2) The last month for which the widow(er) or surviving divorced spouse was entitled to an annuity for having the employee's child in care; or

(3) The last month for which the widow(er) or surviving divorced spouse was entitled to a previous annuity based on disability; and

(b) Ends with the earlier of:

(1) The month before the month in which the widow(er) or surviving divorced spouse or remarried widow(er) become 60 years old; or

(2) The last day of the last month of a 7-year period (84 consecutive months) following the month in which the period began.