How Accelerated Depreciation Works: MACRS, Section 179, and Bonus

Accelerated depreciation works by letting a business deduct a larger share of an asset’s cost in the first years of ownership instead of spreading it evenly across the asset’s useful life. The total write-off is the same either way. What changes is the timing: bigger deductions arrive early, when the cash savings are worth the most. For federal tax purposes, three mechanisms do this work together — the Modified Accelerated Cost Recovery System (MACRS), Section 179 expensing, and bonus depreciation. For 2026, 100% bonus depreciation (restored by the One Big Beautiful Bill Act) and a Section 179 limit near $2.56 million mean many businesses can write off the full cost of qualifying equipment in the year they put it to work.

Why Timing Matters

A deduction today is worth more than the same deduction five years from now. That is the entire reason acceleration exists in the tax code. Congress uses it to encourage capital spending, and businesses use it to improve cash flow in the years when a purchase hits the books. The recovery periods built into MACRS are generally shorter than an asset’s actual physical life, and that gap is deliberate federal policy.

Acceleration is not a free deduction. It is a shift. You still only recover the cost of the asset once, and if you sell the asset later at a gain, the IRS reclaims some of the benefit through recapture rules. More on that below.

MACRS: The Default System

The Modified Accelerated Cost Recovery System is the default depreciation method for federal tax purposes and has applied to most tangible property placed in service since 1987. Businesses must use MACRS unless they specifically elect the Alternative Depreciation System (ADS).¹

MACRS is not a single formula. It assigns each asset a recovery period (how many years you depreciate it over) and a depreciation method (the rate you take deductions each year). For property in the 3-, 5-, 7-, and 10-year classes, MACRS uses the 200% declining balance method — double the straight-line rate, which is what makes it “accelerated.” The system automatically switches to straight-line in the year that calculation produces a bigger deduction, so the full cost is recovered by the end of the recovery period. Property in the 15- and 20-year classes uses the slightly less aggressive 150% declining balance method.²

When Depreciation Starts: Conventions

MACRS uses conventions to decide when your depreciation clock starts within a year. The most common is the half-year convention: every asset placed in service during the year is treated as though you started using it at the midpoint, giving you half a year’s depreciation in year one and half in the final year.³

An anti-abuse rule changes that if more than 40% of your total depreciable property for the year is placed in service during the last three months. In that case, the mid-quarter convention kicks in, assigning a midpoint to the specific quarter each asset was placed in service. The result is usually a smaller first-year deduction for property bought late in the year. Real property uses the mid-month convention, keyed to the month the building is placed in service.

Property Classes and What Actually Accelerates

To qualify for MACRS at all, property must be tangible, used in a trade or business or held to produce income, and have a useful life exceeding one year. Land never qualifies because it does not wear out. Inventory is excluded because its cost is recovered through cost of goods sold. Intangibles like patents and goodwill are amortized under separate rules.

MACRS assigns each qualifying asset to a class with a fixed recovery period:¹

3-year property: certain short-lived assets like tractor units and specialized tools.
5-year property: computers, automobiles, copiers, and research equipment.
7-year property: office furniture, fixtures, and most general-purpose machinery.
10-year property: certain vessels, barges, and single-purpose agricultural structures.
15-year property: land improvements such as fencing, sidewalks, and roads.
20-year property: farm buildings and certain municipal infrastructure.
27.5-year property: residential rental buildings, depreciated straight-line.⁴
39-year property: nonresidential (commercial) real property, straight-line.

Notice the two real property classes use straight-line, not an accelerated method. If you are buying a building, the heavy first-year deductions available on equipment are not on the table through MACRS itself. The acceleration lives in the shorter-life classes.

Section 179: Immediate Expensing Up to a Cap

Section 179 lets a business deduct the full purchase price of qualifying property in the year it is placed in service, up to an annual dollar cap.⁵ The One Big Beautiful Bill Act, signed in July 2025, raised the base statutory limit from $1 million to $2.5 million and the investment phase-out threshold from $2.5 million to $4 million, effective for property placed in service after December 31, 2024. For tax years beginning in 2025, the limits are $2,500,000 and $4,000,000.⁶ For 2026, inflation adjustments push the deduction limit to approximately $2,560,000 and the phase-out threshold to roughly $4,090,000.

The phase-out is dollar-for-dollar. Once your total Section 179 purchases for the year exceed the threshold, the maximum deduction shrinks by a dollar for every dollar above it. Large enough purchases can phase the deduction out entirely.

Qualifying property includes tangible personal property like machinery, equipment, and off-the-shelf software. It also covers certain improvements to nonresidential real property: roofs, HVAC, fire protection and alarm systems, and security systems.²

One limitation catches many business owners off guard. The Section 179 deduction cannot exceed your aggregate taxable income from the active conduct of a trade or business. It cannot create or increase a net operating loss. Any unused portion carries forward.⁷ For partnerships and S corporations, this income test applies at both the entity level and the owner level.

Bonus Depreciation Is Back at 100%

Bonus depreciation changed dramatically in 2025. Under the Tax Cuts and Jobs Act of 2017, the 100% rate had phased down to 80% in 2023, 60% in 2024, and was headed to 40% in 2025. The One Big Beautiful Bill Act reversed that phase-out and permanently restored 100% bonus depreciation for qualifying property acquired and placed in service after January 19, 2025.⁸

Eligible property includes tangible MACRS property with a recovery period of 20 years or less, off-the-shelf computer software, and qualified improvement property. For most businesses buying equipment in 2026, that means the full cost can be written off immediately.

Watch the acquisition date. The 100% rate applies only to property acquired after January 19, 2025. If you contracted to buy equipment before that date but did not place it in service until 2026, the old phase-down schedule still governs the asset, giving you just 20% bonus depreciation for 2026. The acquisition date, not the placed-in-service date, determines the rate.

Unlike Section 179, bonus depreciation has no annual dollar cap and no taxable-income limitation. It can create or deepen a net operating loss that then carries forward. That flexibility makes bonus depreciation the more powerful tool for large purchases, while Section 179 remains useful for businesses that want to control exactly how much they expense in a given year.

How the Three Methods Stack

When a business buys qualifying property, the incentives apply in a specific order. First, you decide how much to expense under Section 179, subject to the dollar cap and the income limit. Next, bonus depreciation applies to any remaining basis at the applicable percentage. Finally, whatever basis is still left enters the standard MACRS schedule and depreciates over the recovery period.

Say a business buys $300,000 of qualifying equipment in 2026. It could elect $300,000 of Section 179 and be done. Or it could skip Section 179 entirely and let 100% bonus depreciation handle the full cost. Both routes produce the same first-year deduction for most purchases. The difference emerges with limited taxable income: Section 179 would be capped at that income, but bonus depreciation would not.

One structural difference matters for planning. The election to take or skip bonus depreciation is made on a class-by-class basis (all 5-year property, all 7-year property, and so on), not asset by asset. Section 179 can be applied selectively to individual assets.

Vehicles and Other Listed Property

Passenger vehicles and other “listed property” face additional restrictions that override the general rules. To claim accelerated depreciation, Section 179, or bonus depreciation on listed property, you must use the asset more than 50% for business during the year it is placed in service. Commuting and personal trips do not count toward business use.²

If business use is 50% or less, you lose access to accelerated methods and must use straight-line over the longer ADS recovery period. If use starts above 50% and later drops to 50% or less during the recovery period, you have to recapture the excess depreciation previously claimed, reporting it as ordinary income on Form 4797.

Even when a passenger vehicle qualifies, Section 280F imposes annual dollar caps. For vehicles placed in service in 2026 where bonus depreciation applies:⁹

Year 1: $20,300
Year 2: $19,800
Year 3: $11,900
Each succeeding year: $7,160

Without bonus depreciation, the first-year cap drops to $12,300, with later years unchanged. These caps apply per vehicle, so a $60,000 car takes several years to fully depreciate even if 100% bonus depreciation would otherwise cover it. Vehicles with a gross vehicle weight rating above 6,000 pounds that are not designed primarily for passenger transport (certain SUVs and trucks) are generally exempt from these caps, though a separate Section 179 dollar limit applies to heavy SUVs.

Recapture When You Sell

The acceleration you take today has a counterweight on the back end. When you sell a depreciated asset at a gain, the IRS reclaims part of the benefit through recapture.

For tangible personal property (equipment, vehicles, machinery), Section 1245 taxes any gain on sale as ordinary income to the extent of all depreciation previously deducted. “All depreciation” includes Section 179 expensing and bonus depreciation, not just regular MACRS.¹⁰ Buy a machine for $100,000, deduct the full cost, sell it later for $40,000, and that $40,000 gain is ordinary income, not capital gain.

Real property follows different rules under Section 1250. Gain attributable to straight-line depreciation on residential rental or commercial buildings is taxed at a maximum 25% rate for individual taxpayers (the “unrecaptured Section 1250 gain” rate). Any gain above the total depreciation taken qualifies for long-term capital gains treatment.

This trade-off is baked in. You get a bigger deduction now at your current marginal rate and give some of it back on disposition. The time value of money usually makes acceleration worthwhile anyway: a dollar saved today is worth more than a dollar owed in five or ten years.

A Note on ADS

Everything above describes the General Depreciation System, which is the default and the source of acceleration. Certain property must instead use the Alternative Depreciation System, which uses straight-line over longer recovery periods. ADS is mandatory for property used predominantly outside the United States, tax-exempt use property, tax-exempt bond-financed property, certain farming property held by an electing farming business, and imported property covered by an executive order. A business may also elect ADS voluntarily, but once elected for a particular asset the choice is generally irrevocable.

State Taxes Don’t Automatically Follow

Federal depreciation rules do not automatically carry over to state income taxes. States range from full conformity with federal bonus depreciation and Section 179 to complete nonconformity, where businesses must add back federal accelerated deductions and use standard schedules for state purposes. A business in a nonconforming state could owe state tax on income that was sheltered federally. Check your state’s conformity position before building federal depreciation projections into your cash flow planning; the difference can run into thousands of dollars.

1
Office of the Law Revision Counsel. 26 USC 168 – Accelerated Cost Recovery System
2
Internal Revenue Service. Publication 946 – How To Depreciate Property
3
eCFR. 26 CFR 1.168(d)-1 – Half-Year and Mid-Quarter Conventions
4
Internal Revenue Service. Depreciation and Recapture
5
Office of the Law Revision Counsel. 26 USC 179 – Election To Expense Certain Depreciable Business Assets
6
Internal Revenue Service. Instructions for Form 4562
7
eCFR. 26 CFR 1.179-2 – Limitations on Amount Subject to Section 179 Election
8
Internal Revenue Service. One, Big, Beautiful Bill Provisions
9
Internal Revenue Service. Revenue Procedure 2026-15
10
Office of the Law Revision Counsel. 26 USC 1245 – Gain From Dispositions of Certain Depreciable Property