(a) A claim for benefits filed under this part by, or on behalf of, a miner shall be filed within three years after a medical determination of total disability due to pneumoconiosis which has been communicated to the miner or a person responsible for the care of the miner, or within three years after the date of enactment of the Black Lung Benefits Reform Act of 1977, whichever is later. There is no time limit on the filing of a claim by the survivor of a miner.

(b) There shall be a rebuttable presumption that every claim for benefits is timely filed. The time limits in this section are mandatory and may not be waived or tolled except upon a showing of extraordinary circumstances.