Title II — TAX ON INCOME (2) Election to Deduct Exploration and Development Expenditures. — In computing taxable income from mining operations, the taxpayer may, at his option, deduct exploration and development expenditures accumulated as cost or adjusted basis for cost depletion as of date of prospecting, as well as exploration and development expenditures paid or incurred during the taxable year: Provided, That the total amount deductible for exploration and development expenditures shall not exceed twenty-five percent (25%) of the net income from mining operations computed without the benefit of any tax incentives under existing laws. The actual exploration and development expenditures minus twenty-five percent (25%) of the net income from mining shall be carried forward to the succeeding years until fully deducted. The election by the taxpayer to deduct the exploration and development expenditures is irrevocable and shall be binding in succeeding taxable years. ‘Net income from mining operations’, as used in this Subsection, shall mean gross income from operations less ‘allowable deductions’ which are necessary or related to mining operations. ‘Allowable deductions’ shall include mining, milling and marketing expenses, and depreciation of properties directly used in the mining operations. This paragraph shall not apply to expenditures for the acquisition or improvement of property of a character which is subject to the allowance for depreciation. In no case shall this paragraph apply with respect to amounts paid or incurred for the exploration and development of oil and gas. The term ‘exploration expenditures’ means expenditures paid or incurred for the purpose of ascertaining the existence, location, extent, or quality of any deposit of ore or other mineral, and paid or incurred before the beginning of the development stage of the mine or deposit. The term ‘development expenditures’ means expenditures paid or incurred during the development stage of the mine or other natural deposits. The development stage of a mine or other natural deposit shall begin at the time when deposits of ore or other minerals are shown to exist in sufficient commercial quantity and quality and shall end upon commencement of actual commercial extraction. (3) Depletion of Oil and Gas Wells and Mines Deductible by a Nonresident Alien Individual or Foreign Corporation. — In the case of a National Internal Revenue Code of 1997 (as amended by the TRAIN Law, RAs 11256, 11346 and 11467) 55