(a) With respect to property placed in service in taxable years ending prior to the effective date of this Code section, a taxpayer shall in his return for the first taxable year ending on or after January 1, 1987, elect to:

(1) Continue to depreciate or otherwise recover the cost of such property according to the same method used for Georgia income tax purposes for the taxable year in which the property was placed in service; or

(2) Depreciate or otherwise recover the cost of such property according to the method used for federal income tax purposes for the taxable year in which the property was placed in service.

The election required by this subsection shall be made for a taxpayer's first taxable year ending on or after January 1, 1987, in such manner as may be specified by the commissioner. If a return for such a taxable year has been filed without such an election prior to or within 90 days after the effective date of this Code section, the taxpayer may file an amended return containing such an election.

(b) The election provided for in subsection (a) of this Code section shall apply to all property of the taxpayer uniformly and shall be irrevocable and applicable to all subsequent taxable years. Except as otherwise provided in the last sentence of subsection (a) of this Code section, if no such election is made, the taxpayer shall be deemed to have elected the option afforded by paragraph (2) of subsection (a) of this Code section. The General Assembly recognizes and intends that if a taxpayer elects the option afforded by paragraph (2) of subsection (a) of this Code section then in certain cases the taxpayer may never fully depreciate or recover the cost of certain property for Georgia income tax purposes and in certain cases the taxpayer may be allowed to depreciate or recover more than the full cost of certain property for Georgia income tax purposes. Taxpayers electing the option afforded by paragraph (1) of subsection (a) of this Code section shall in determining Georgia taxable income make such adjustments to federal taxable income as are required to reflect the effect of such election. Any such election shall apply both to determination of deductions for depreciation or cost recovery of affected property and also to determination of gain or loss on the sale or other disposition of such property. The commissioner shall specify the manner in which such adjustments shall be made.