418 U.S. 1 (U.S. Supreme Court 1974)
Commissioner v. Idaho Power Co.
When a taxpayer uses its own depreciable equipment in constructing or improving capital facilities, must the depreciation attributable to that use be capitalized into the basis of the constructed assets under § 263, or may it be currently deducted under § 167?
Amounts paid or incurred for new buildings or for permanent improvements or betterments that increase the value of property must be capitalized and are not currently deductible. I.R.C. § 263(a)(1); Treas. Reg. § 1.263(a)-1. Although § 167 allows a deduction for depreciation of property used in a trade or business, that allowance operates in harmony with § 263; costs properly allocable to the construction or production of a capital asset are capital expenditures and must be added to basis and recovered over time. See I.R.C. §§ 1012, 1016, 167, 263.
Depreciation attributable to the use of a taxpayer's equipment in the construction or improvement of its own capital facilities is a capital expenditure under § 263 and must be capitalized into the basis of the constructed assets, to be recovered through depreciation on those assets; it may not be deducted currently under § 167.
The decision establishes a key principle of tax accounting: costs must be capitalized when they are properly allocable to constructing or improving a capital asset, including depreciation on equipment used in that activity. It is widely cited for the proposition that § 263's capitalization mandate can and does limit otherwise available deductions. The case is a doctrinal ancestor to the later-enacted uniform capitalization rules under § 263A, which broadly require capitalization of direct and certain indirect production costs. For students, Idaho Power is essential for understanding the timing of deductions, the matching principle, and how courts reconcile overlapping Code provisions and Treasury regulations.