(a) In general. If the taxpayer so elects with respect to all mines with respect to which deductions have been allowed under section 617(a) and which reach the producing stage during a taxable year, he shall include in gross income for the taxable year an amount equal to the adjusted exploration expenditures with respect to such mines (determined under section 617(f)(1)). The amount so included in income shall be treated for purposes of Subtitle A of the Internal Revenue Code as expenditures which are paid or incurred on the respective dates on which the mines reach the producing stage and which are properly chargeable to capital account. If the taxpayer does not make this election for a taxable year during which any mine with respect to which deductions have been allowed under section 617(a) reaches the producing stage, the deduction for depletion under section 611 with respect to the property (whether determined under §1.611-2 of this chapter (Income Tax Regulations) or under section 613) shall be disallowed until the amount of depletion which would be allowable but for section 617(b)(1)(B) equals the amount of the adjusted exploration expenditures with respect to the mine. The fact that a taxpayer does not make the election described in the first sentence of this paragraph for a taxable year during which mines with respect to which deductions have been allowed under section 617(a) reach the producing stage shall not preclude the taxpayer from making the election with respect to other mines which reach the producing stage during a subsequent taxable year. However, an election may not be made for any taxable year with respect to any mines which reached the producing stage during a preceding taxable year.

(b) Manner of making elections. A taxpayer will be considered to have made an election in accordance with the manner in which the adjusted exploration expenditures with respect to the mines reaching the producing stage during a taxable year are treated in his return for such taxable year.

(c) Time for making election. The election described in paragraph (a) of this section may be made, or changed by filing an amended return, not later than the time prescribed by law for filing the return (including extensions thereof) for the taxable year.