20 C.F.R. § 725.305 : Employees' Benefits — OFFICE OF WORKERS' COMPENSATION PROGRAMS, DEPARTMENT OF LABOR — FEDERAL COAL MINE HEALTH AND SAFETY ACT OF 1969, AS AMENDED — CLAIMS FOR BENEFITS UNDER PART C OF TITLE IV OF THE FEDERAL MINE SAFETY AND HEALTH ACT, AS AMENDED — FILING OF CLAIMS — When a written statement is considered a claim

(a) The filing of a statement signed by an individual indicating an intention to claim benefits shall be considered to be the filing of a claim for the purposes of this part under the following circumstances:
(1) The claimant or a proper person on his or her behalf (see §725.301 ) executes and files a prescribed claim form with the Office during the claimant's lifetime within the period specified in paragraph (b) of this section.
(2) Where the claimant dies within the period specified in paragraph (b) of this section without filing a prescribed claim form, and a person acting on behalf of the deceased claimant's estate executes and files a prescribed claim form within the period specified in paragraph (c) of this section.
(b) Upon receipt of a written statement indicating an intention to claim benefits, the Office shall notify the signer in writing that to be considered the claim must be executed by the claimant or a proper party on his or her behalf on the prescribed form and filed with the Office within six months from the date of mailing of the notice.
(c) If before the notice specified in paragraph (b) of this section is sent, or within six months after such notice is sent, the claimant dies without having executed and filed a prescribed form, or without having had one executed and filed in his or her behalf, the Office shall upon receipt of notice of the claimant's death advise his or her estate, or those living at his or her last known address, in writing that for the claim to be considered, a prescribed claim form must be executed and filed by a person authorized to do so on behalf of the claimant's estate within six months of the date of the later notice.
(d) Claims based upon written statements indicating an intention to claim benefits not perfected in accordance with this section shall not be processed.

20 C.F.R. § 725.305