(1) Method of determining amounts referred to in subsection (b) (A) In general The amounts described in subsection (b) shall be determined by using reasonable actuarial methods and assumptions which are not inconsistent with regulations prescribed by the Secretary. (B) Funding period Except as provided in subparagraph (C), the funding period for purposes of subsection (b)(1) shall be the greater of— (i) the average remaining working life of miners who are present employees of the taxpayer, or (ii) 10 taxable years. For purposes of the preceding sentence, the term “miner” has the same meaning as such term has when used in section 402(d) of the Black Lung Benefits Act ( 30 U.S.C. 902(d) ). (C) Different funding periods To the extent that— (i) regulations prescribed by the Secretary provide for a different period, or (ii) the Secretary consents to a different period proposed by the taxpayer, such different period shall be substituted for the funding period provided in subparagraph (B).