La. Revenue and Taxation § 47:66
In computing net income in the case of mines, oil and gas wells, other natural deposits, and timber a reasonable allowance for depletion and for depreciation of improvements, according to the peculiar conditions in each case, shall be allowed as a deduction; such reasonable allowances in all cases to be made under rules and regulations to be prescribed by the collector. In any case in which it is ascertained, as a result of operations or of development work, that the recoverable units are greater or less than the prior estimate thereof, then such prior estimate, but not the basis for depletion, shall be revised and the allowance under this Section for subsequent taxable years shall be based upon such revised estimate. In the case of leases the deductions shall be equitably apportioned between the lessor and lessee. In the case of property held by one person for life, with remainder to another person, the deduction shall be computed as if the life tenant were the absolute owner of the property and shall be allowed to the life tenant. In the case of property held in trust, the allowable deduction shall be apportioned between the income beneficiaries and the trustee in accordance with the pertinent provisions of the instrument creating the trust, or, in the absence of such provisions, on the basis of the trust income allocable to each.
The basis upon which depletion is to be allowed in respect of any property shall be as provided in R.S. 47:158.
La. Revenue and Taxation § 47:66