# Depreciation **The model:** The accounting recognition that physical assets lose value over time as they're used up, wear out, or become obsolete. A piece of equipment that costs $100,000 and has a 10-year useful life is treated as a $10,000 expense per year for accounting purposes (if depreciated on a straight-line basis), even though no cash leaves the business each year. Depreciation matches the *cost* of using an asset to the *period* over which it's used, providing a more accurate picture of economic profitability than simply recording the full purchase as an expense in year one. The political and tax-policy importance comes from depreciation rules' interaction with corporate tax. The U.S. tax code allows businesses to deduct depreciation against taxable income; the *speed* at which depreciation can be claimed (accelerated depreciation, bonus depreciation, immediate expensing) substantially affects the effective tax rate on capital investment. The 2017 Tax Cuts and Jobs Act made 100% bonus depreciation available for many types of property, which functioned as a major corporate tax cut even before the headline rate reduction. ## The Mechanism **Straight-line vs. accelerated.** Straight-line depreciation spreads the cost evenly across the asset's useful life. Accelerated methods (declining-balance, sum-of-years' digits, MACRS) front-load the deductions, providing larger tax benefits in early years. The choice affects timing, not total deductions — but timing matters because of [[Compound Interest]] effects on the deferred tax. **Bonus depreciation and immediate expensing.** Some tax provisions allow immediate expensing of asset purchases — the entire cost deducted in year one. This is economically equivalent to a zero corporate tax rate on the affected capital investment (because the deduction's present value equals the eventual tax-shield's present value). The 2017 TCJA's 100% bonus depreciation for most non-real-estate property was effectively a major corporate tax cut delivered through depreciation rules rather than rate changes. **Real estate and the special rules.** Real estate has its own depreciation rules — residential rental property over 27.5 years, commercial property over 39 years, both straight-line. Combined with the step-up in basis at death and 1031 like-kind exchanges, real estate depreciation is one of the most tax-favored investment categories in the U.S. The structural advantages compound across generations. **Economic vs. tax depreciation.** Tax depreciation rules don't necessarily match economic reality. An asset's actual useful life may be longer or shorter than the tax-code specification. The gap creates opportunities for tax arbitrage and produces the interesting situation where a profitable business can show "losses" for tax purposes due to depreciation deductions. [[Donald Trump]]'s tax returns famously showed this pattern across multiple decades. ## KB Applications ### Real Estate Depreciation and the Trump Tax Pattern Donald Trump's leaked tax returns showed an unusually long pattern of declared losses, much of which was driven by real-estate depreciation deductions. Real estate generates physical wear and obsolescence that produces depreciation deductions; if the asset's market value is *appreciating* (which most real estate has been doing), the result is a property that's gaining value while generating tax losses. Combined with leverage, this pattern can produce decades of "negative income" for tax purposes from properties that are throwing off positive cash. The tax system's treatment of real estate is uniquely generous. ### Bonus Depreciation as Hidden Corporate Tax Cut The 2017 TCJA's headline corporate-rate cut from 35% to 21% received most of the political attention. The bonus-depreciation provision was less publicized but quantitatively comparable — and by some measures more economically significant for high-investment industries. The provision phases out (80% in 2023, 60% in 2024, 40% in 2025, 20% in 2026, 0% thereafter); restoring it has been a major Republican tax-policy priority. The fact that depreciation rules are technical and obscure protects them from popular debate even though their fiscal cost is enormous. ### Why Depreciation Matters for Capital-vs-Labor Tax Comparisons Effective tax-rate calculations on capital must account for depreciation. A corporate income tax with full immediate expensing of capital purchases is functionally equivalent to a *consumption tax* on the corporation — which is a much lower-rate tax than a true income tax. Many U.S. industries face effective marginal corporate tax rates near zero or below zero on new investment, due to the combination of bonus depreciation, interest deductibility, and other features. Headline corporate tax rates significantly overstate the true tax burden. ## See Also - [[Appreciation]] — the structural opposite (assets gaining value) - [[Compound Interest]] — what makes timing of deductions matter - [[Capital Gains]] — the related capital-tax treatment