Useful Life of an Asset: MACRS Classes, Section 179, and Bonus Depreciation

For tax purposes, the useful life of an asset is not something you estimate. The IRS assigns each type of business property a fixed recovery period under the Modified Accelerated Cost Recovery System (MACRS), and that period controls how many years you spread the cost across as a depreciation deduction. A computer gets five years whether you replace it in three or run it for seven. An office desk gets seven. A warehouse gets 39. Classify the asset correctly and the math follows; classify it wrong and every year’s deduction is wrong with it.

Why Tax Useful Life Differs From Accounting Useful Life

In financial accounting under GAAP, useful life is a judgment call. You pick a period based on how long the asset is expected to serve your specific operations, and you usually depreciate it on a straight line down to an estimated salvage value. That number lives on your financial statements.

Tax depreciation ignores all of that. MACRS groups property into classes by type, assigns each class a recovery period, and applies accelerated methods that front-load the deductions into the earlier years. Two businesses buying the same equipment use the same recovery period regardless of how hard either one runs it. Salvage value is disregarded entirely under MACRS: you depreciate the full basis down to zero.

Because the two systems produce different numbers, most businesses maintain two depreciation schedules, one for the books and one for the return.

MACRS Property Classes and Recovery Periods

MACRS recovery periods run from 3 years to 39 years. The common classes:

3-year property: over-the-road tractor units, racehorses over two years old, and certain manufacturing tools with a short class life.
5-year property: automobiles, taxis, buses, computers and peripherals, copiers, and other general-purpose office technology.
7-year property: office furniture and fixtures such as desks, filing cabinets, and safes; used agricultural machinery placed in service after 2017; grain bins and farm fences.
15-year property: qualified improvement property (interior improvements to nonresidential buildings), land improvements like sidewalks and parking lots, and certain communication equipment.
25-year property: water utility property used in gathering, treatment, or commercial distribution of water.
27.5-year property: residential rental buildings.
39-year property: nonresidential real property, including office buildings, warehouses, and retail stores.

The split between personal property (equipment, vehicles, furniture) and real property (buildings and structural components) drives most of the practical difference. Personal property lands in the shorter classes and qualifies for accelerated methods and the immediate-expensing provisions below. Real property gets the long recovery periods and must be depreciated straight-line.¹

GDS vs. ADS

MACRS contains two systems. The General Depreciation System (GDS) is the default and produces faster deductions through accelerated methods. The Alternative Depreciation System (ADS) uses straight-line depreciation over longer recovery periods, which means smaller annual deductions spread over more years.

Most taxpayers stay with GDS because larger deductions earlier mean lower taxes now. ADS is mandatory for property used predominantly outside the United States, tax-exempt use property, and property financed with tax-exempt bonds. You can also elect ADS voluntarily, but that election is generally irrevocable for the property involved.¹

First-Year Conventions

MACRS doesn’t assume you placed the asset in service on January 1. A convention decides how much of the first year’s depreciation you actually get.

Half-year convention: the default for most personal property. Every asset is treated as placed in service at the midpoint of the year, so you claim half a year’s depreciation in both the first and last year.
Mid-quarter convention: triggered when more than 40% of the year’s personal-property additions were placed in service in the last three months. Each asset is then treated as placed in service at the midpoint of the quarter it actually entered use, which prevents fourth-quarter bunching.
Mid-month convention: required for residential rental property and nonresidential real property. The building is treated as placed in service at the midpoint of the month it was actually placed in service.

Identify the right convention before you run the numbers; it changes the first-year deduction and which depreciation table applies.¹

When You Can Skip the Recovery Period Entirely

For many small businesses, spreading a purchase over its full MACRS life is the wrong answer. Three provisions let you write the cost off much sooner, or immediately.

Section 179

Section 179 lets you deduct the full purchase price of qualifying property in the year you place it in service, up to an annual dollar limit. For 2025, the maximum deduction is $2,500,000, with a phase-out beginning when total qualifying property placed in service exceeds $4,270,000. These limits adjust for inflation.²

Qualifying property is tangible personal property used in an active trade or business. Investment property and property acquired by gift or inheritance do not qualify. Certain nonresidential real property improvements do qualify, including roofs, HVAC systems, fire protection and alarm systems, and security systems. Your Section 179 deduction can’t exceed your taxable income from all active trades or businesses, but any amount you can’t use carries forward.¹

Bonus Depreciation

Bonus depreciation has no dollar cap and works alongside Section 179. The One Big Beautiful Bill Act, signed in 2025, restored 100% bonus depreciation for qualified property acquired after January 19, 2025. Property acquired before January 20, 2025 but placed in service in 2026 still falls under the old phase-down schedule, limiting bonus depreciation to 20% for that property. Unlike Section 179, bonus depreciation can create or increase a net operating loss.³

The De Minimis Safe Harbor

Low-cost items don’t need to enter the depreciation system at all. Under the de minimis safe harbor, a business with an applicable financial statement can expense items costing up to $5,000 per invoice; without audited financials, the threshold is $2,500 per invoice or item. You elect the safe harbor annually on your return, and once elected it applies to all qualifying expenditures for the year.⁴

What the Recovery Period Costs You at Sale

Depreciation delivers deductions while you own the asset. When you sell at a gain, the IRS takes some of that benefit back through depreciation recapture.

For depreciable personal property under Section 1245, the gain attributable to prior depreciation is taxed as ordinary income rather than at capital-gains rates. The recapture amount is the lesser of your total gain or the total depreciation claimed. Buy a machine for $50,000, depreciate it down to $10,000, sell it for $35,000: the entire $25,000 gain is ordinary income, because it sits within the $40,000 of depreciation you already took.⁵

Real property under Section 1250 works differently. Because MACRS depreciates buildings on a straight line, there is generally no excess depreciation to recapture as ordinary income. But the depreciation you did claim is taxed at a special 25% rate as unrecaptured Section 1250 gain when you sell at a profit. Any gain above the total depreciation qualifies for standard long-term capital gains rates.⁶

The “Allowed or Allowable” Rule

The trap worth knowing about before you skip a year: the IRS reduces your basis by depreciation “allowed or allowable,” whichever is greater. Forget to claim depreciation for several years and the IRS still treats your basis as though you took it. At sale, you owe recapture on deductions you never actually received.⁷

The remedy is to catch missed depreciation before the sale. Form 3115 lets you change your method or correct prior-year errors and claim the missed depreciation as a single catch-up deduction through a Section 481(a) adjustment, rather than amending each earlier return.⁸ The point for anyone deciding how to handle useful life on a return: claiming depreciation is not really optional. The tax bill on the sale assumes you took it either way.

1
Internal Revenue Service. Publication 946 (2025), How To Depreciate Property
2
Internal Revenue Service. Instructions for Form 4562 (2025)
3
Internal Revenue Service. Interim Guidance on Additional First Year Depreciation Deduction
4
Internal Revenue Service. Tangible Property Final Regulations
5
Office of the Law Revision Counsel. 26 U.S. Code 1245 – Gain From Dispositions of Certain Depreciable Property
6
Internal Revenue Service. Publication 544 (2025), Sales and Other Dispositions of Assets
7
Internal Revenue Service. Depreciation Recapture 3
8
Internal Revenue Service. Instructions for Form 3115 (Rev. December 2022)