20 CFR §216.81

1. (a)Where the employee is not survived by a widow(er), or child who is or ever could be entitled to an annuity as described by subpart G or H of this part, a parent of the deceased employee is eligible for both the tier I and tier II components of an annuity if he or she:
   1. (1)Is age 60 or older;
   2. (2)Has not married since the employee died;
   3. (3)Received one-half of his or her support (as defined in part 222 of this chapter) from the employee at the time the employee died; and
   4. (4)Files proof of support as provided for in paragraphs (b)(4) and (b)(5) of this section.
2. (b)Where the employee is survived by a widow(er), or child who is or ever could be entitled to an annuity as described by subpart G or H of this part, a parent of the deceased employee is eligible for an annuity consisting of the tier I component alone if he or she:
   1. (1)Is age 60 or older;
   2. (2)Has not married since the employee died;
   3. (3)Is not in receipt of an old age benefit under the Social Security Act equal to or exceeding the amount of the parent's tier I annuity amount before it is reduced for the family maximum but after the sole survivor minimum is considered;
   4. (4)Received at least one-half of his or her support (as defined in part 222 of this chapter) from the employee either:
      1. (i)When the employee died, or
      2. (ii)At the beginning of the period of disability if the employee has a period of disability (as explained in part 220 of this chapter) which did not end before death; and
   5. (5)Files proof of support with the Board within 2 years after either:
      1. (i)The month in which the employee filed an application for a period of disability if support is to be established as of the beginning of the period of disability; or
      2. (ii)The date of the employee's death if support is to be established at that point.
3. (c)The Board may accept proof of support filed after the 2-year period for reasons which constitute good cause to do so as that term is defined in part 219 of this chapter.