Section 179: Definition, How It Works, and Example

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Section 179 is a provision of the U.S. Internal Revenue Code that lets a business deduct the full cost of qualifying equipment, software and certain other property in the year it is placed in service, instead of depreciating it over several years. The deduction is an election: the business chooses which assets to expense and how much of each, within dollar and income limits. It applies even to financed assets, so a business can deduct equipment it has not finished paying for.

How Section 179 Works

Normally, a business capitalizes a long-lived asset and recovers the cost through annual depreciation, usually under MACRS. Section 179 lets it expense some or all of that cost immediately. The total deduction over the asset’s life stays the same. Only the timing changes: more of it is pulled into the current year, lowering current taxable income.

The property must be placed in service (ready and available for use) during the tax year of the claim, so equipment bought in December but installed in January is deducted the following year. The election is made on IRS Form 4562, filed with the return.

The three limits

1. Dollar limit. For tax year 2025, the cap is $2,500,000. The IRS adjusts it for inflation in later years.
2. Phase-out. The cap drops dollar for dollar once the cost of Section 179 property placed in service during the year exceeds $4,000,000. With 2025 figures, it reaches zero at $6,500,000 of qualifying purchases.
3. Business income limit. The deduction cannot exceed taxable income from the active conduct of your trades or businesses, so it cannot create or increase a business loss. Any disallowed amount carries forward to future years.

Business-use percentage

The asset must be used for business more than 50% of the time, and only the business-use share of the cost is eligible. A $60,000 machine used 80% for business supports up to $48,000 of Section 179 expense.

Example of Section 179

Hypothetical example, using the 2025 limits and ignoring state tax.

A company buys a $50,000 machine, uses it 100% for business and places it in service in 2025. A simplified five-year straight-line schedule with no salvage value would give $10,000 a year. With a Section 179 election, it can deduct the full $50,000 in 2025, provided its business taxable income for the year is at least $50,000.

If its business income before this deduction is only $30,000, it can deduct $30,000 under Section 179 and carry the other $20,000 forward. Alternatively, it can expense $30,000 and depreciate the rest.

In a phase-out case, a larger firm places $4,300,000 of qualifying property in service in 2025. That is $300,000 over the threshold, so its maximum Section 179 deduction falls from $2,500,000 to $2,200,000.

What Property Qualifies

Eligible Section 179 property includes:

• Tangible personal property, such as machinery, equipment, furniture and computers
• Other tangible property the IRS designates
• Single-purpose agricultural (livestock) or horticultural structures
• Storage facilities used in distributing petroleum or its primary products
• Off-the-shelf computer software
• Qualified real property, which covers qualified improvement property and certain improvements to nonresidential real property such as roofs, HVAC, fire protection and alarm systems, and security systems

The property must be acquired for use in a trade or business. Property acquired only to produce income does not qualify. That excludes investment property, royalty-producing property, and rental property when renting is not your trade or business. A landlord who runs rentals as a business may qualify for furnishings and equipment. Someone holding a single rental as an investment generally cannot.

Vehicles and SUVs

Cars, trucks and SUVs are eligible when business use exceeds 50%, but passenger vehicles face separate depreciation caps. For heavy SUVs, Section 179 expense is capped at $31,300 for tax year 2025. Any remaining cost may be recovered through bonus or regular depreciation.

Who cannot use it

Estates and trusts are not allowed to claim the Section 179 deduction.

Section 179 vs. Bonus Depreciation vs. Regular Depreciation

• Regular depreciation (MACRS) spreads the deduction over the asset’s recovery period, such as five or seven years depending on the asset class.
• Section 179 is elective, can be applied asset by asset, and is subject to the dollar cap, the phase-out and the business income limit.
• Bonus depreciation is a separate first-year allowance with no annual dollar cap and no business income limit, so it can create a net operating loss. It applies automatically unless the business elects out for a class of property, and its percentage has changed under different tax laws.

When both are used, Section 179 is applied first, bonus depreciation applies to the remaining basis, and regular depreciation covers whatever is left. This lets a business fine-tune how much it deducts now.

Limitations of Section 179

Recapture. If business use of a Section 179 asset falls to 50% or less in a later year of its recovery period, part of the earlier deduction is recaptured and added back to income.

Basis reduction. Expensing an asset reduces its tax basis, often to zero. When the asset is sold, the gain is typically taxed as ordinary income up to the amount previously deducted.

Timing trade-off. A large deduction now leaves less depreciation for later years. If the business expects to be in a higher bracket in the future, spreading deductions may be worth more.

State rules. States set their own depreciation rules, and some do not follow the federal Section 179 limits, so the state deduction can differ from the federal one.

Not a cash rebate. The deduction lowers taxable income, not tax owed dollar for dollar. Its value depends on the business’s marginal tax rate, and buying equipment solely to capture a deduction still costs more cash than it saves.

The Bottom Line

Section 179 matters most to businesses buying equipment, software or building improvements that want a larger deduction in the year of purchase. It changes the timing of deductions, not their total, and comes with recapture risk, basis reduction and state rules that may differ. A business with enough taxable income and steady business use can benefit, but buying assets only to capture the deduction still costs more cash than it saves.