Additional depreciation defined

The term “additional depreciation” means, in the case of any property, the depreciation adjustments in respect of such property; except that, in the case of property held more than one year, it means such adjustments only to the extent that they exceed the amount of the depreciation adjustments which would have resulted if such adjustments had been determined for each taxable year under the straight line method of adjustment.

In the case of a lessee, in determining the depreciation adjustments which would have resulted in respect of any building erected (or other improvement made) on the leased property, or in respect of any cost of acquiring the lease, the lease period shall be treated as including all renewal periods. For purposes of the preceding sentence—

(A) the term “renewal period” means any period for which the lease may be renewed, extended, or continued pursuant to an option exercisable by the lessee, but

(B) the inclusion of renewal periods shall not extend the period taken into account by more than ⅔ of the period on the basis of which the depreciation adjustments were allowed.

The term “depreciation adjustments” means, in respect of any property, all adjustments attributable to periods after December 31, 1963 , reflected in the adjusted basis of such property on account of deductions (whether in respect of the same or other property) allowed or allowable to the taxpayer or to any other person for exhaustion, wear and tear, obsolescence, or amortization (other than amortization under section 168 (as in effect before its repeal by the Tax Reform Act of 1976), 169, 185 (as in effect before its repeal by the Tax Reform Act of 1986), 188 (as in effect before its repeal by the Revenue Reconciliation Act of 1990), 190, or 193). For purposes of the preceding sentence, if the taxpayer can establish by adequate records or other sufficient evidence that the amount allowed as a deduction for any period was less than the amount allowable, the amount taken into account for such period shall be the amount allowed.

The term “additional depreciation” also means, in the case of section 1250 property with respect to which a depreciation or amortization deduction for rehabilitation expenditures was allowed under section 167(k) (as in effect on the day before the date of the enactment of the Revenue Reconciliation Act of 1990) or 191 (as in effect before its repeal by the Economic Recovery Tax Act of 1981), the depreciation or amortization adjustments allowed under such section to the extent attributable to such property, except that, in the case of such property held for more than one year after the rehabilitation expenditures so allowed were incurred, it means such adjustments only to the extent that they exceed the amount of the depreciation adjustments which would have resulted if such adjustments had been determined under the straight line method of adjustment without regard to the useful life permitted under section 167(k) (as in effect on the day before the date of the enactment of the Revenue Reconciliation Act of 1990) or 191 (as in effect before its repeal by the Economic Recovery Tax Act of 1981).

For purposes of paragraph (1), the depreciation adjustments which would have resulted for any taxable year under the straight line method shall be determined—

(A) in the case of property to which section 168 applies, by determining the adjustments which would have resulted for such year if the taxpayer had elected the straight line method for such year using the recovery period applicable to such property, and

(B) in the case any property to which section 168 does not apply, if a useful life (or salvage value) was used in determining the amount allowable as a deduction for any taxable year, by using such life (or value).