20 CFR § 219.56
When evidence of a parent's support is required
February 18, 2021
If a person applies for a parent's annuity, the Board will require evidence to show that the parent received at least one-half of his or her support from the employee in the one-year period before—
(a) The employee died; or
(b) The beginning of a period of disability if the employee had a period of disability which did not end before his or her death.