A Refresher on the Section 179 Deduction

                                       

By: Eliezer Gross

Partner, Tax

Key Takeaways

• For tax years beginning in 2025, the Section 179 maximum deduction is $2,500,000, reduced dollar-for-dollar once total qualifying property placed in service exceeds $4,000,000.
• Section 179 does not apply to the building itself — but it can apply to certain nonresidential improvements (including roofs, HVAC, fire protection/alarm systems, and security systems) placed in service after the building was first placed in service.
• Trust/estate limitation: The Section 179 election is not available to trusts and estates, and they generally cannot deduct Section 179 amounts allocated from a partnership or S corporation.
• OBBBA update: IRS guidance under Notice 2026-11 reflects that 100% bonus depreciation is permanently restored for eligible depreciable property acquired after January 19, 2025, with transition elections available in certain situations.
  

Most property owners know Section 179 as the rule that lets businesses write off equipment purchases immediately rather than depreciating them over years. Fewer know it also applies — selectively and under specific conditions — to certain building improvements. Even fewer know where the line is.

That line matters. Cross it and you may have an unsupported deduction. Stay too far inside it and you may defer tax benefits you didn’t need to.

Here’s the precise picture.

Overview

Section 179 allows a taxpayer to expense the cost of qualifying property in the year it is placed in service, rather than recovering that cost through depreciation over time. For tax years beginning in 2025, the maximum Section 179 deduction is $2,500,000. That ceiling phases out dollar-for-dollar once total Section 179 property placed in service during the year exceeds $4,000,000 — meaning at $6,500,000 in qualifying property, the deduction is fully phased out.

The Section 179 election is made by completing Form 4562 with the tax return for the year the property is placed in service.

What Section 179 does not cover: the building itself and its structural components. You cannot use Section 179 to expense the cost of a newly acquired commercial building, a new construction project, or the structural shell of an existing building.

Use requirement: Section 179 generally requires business use (and typically more than 50% business use). It is not designed for property that is merely held for investment.

Who typically claims the Section 179 deduction

The Section 179 deduction is commonly claimed by the taxpayer that owns the property. In real estate structures, that taxpayer is often a partnership or an S corporation, with the deduction flowing through to the owners.

Important ownership limitation: The Section 179 election is not available to trusts and estates. As a result, a partner or shareholder that is a trust or estate generally may not deduct its allocable share of a Section 179 expense elected by a partnership or S corporation — even if that amount is reported on a Schedule K-1. This is a common trap in real estate structures owned through trusts for estate planning or asset protection purposes.

The Four Qualifying Improvement Categories

“Qualified Section 179 real property” includes Qualified Improvement Property (QIP) (as defined in Section 168(e)(6)) and four specific categories of improvements to nonresidential real property — provided the improvements are placed in service after the building was first placed in service. That timing requirement is non-negotiable.

The four categories are:

1. Roofs
   Improvements to the roof of a nonresidential building can qualify, provided the improvement is placed in service after the building was first placed in service. Because roof projects often bundle multiple scopes, cost detail and documentation should clearly support what was placed in service and when.
2. Heating, ventilation, and air-conditioning (HVAC) property
   Qualifying HVAC improvements to nonresidential buildings are eligible. This is particularly valuable for commercial property owners replacing aging systems, as HVAC units represent a significant capital expenditure that would otherwise be recovered over time.
3. Fire protection and alarm systems
   Systems installed or upgraded after the building was placed in service can qualify for the Section 179 deduction. This includes sprinkler systems, fire detection equipment, and fire-safety-specific alarm infrastructure.
4. Security systems
   Property installed to protect the building and its occupants — including access control systems, surveillance equipment infrastructure, and alarm systems — can qualify under this category.
   

Nonresidential requirement: In each case, the improvement must be to nonresidential real property. Residential rental property is not eligible for these four categories under Section 179.

Also eligible (outside real property improvements): tangible personal property used in an active trade or business may be eligible for the Section 179 deduction, and certain software may also qualify.

The Income Limitation: A Hard Stop

Section 179 is limited to the taxpayer’s taxable income from the active conduct of a trade or business. In other words, the Section 179 deduction generally cannot create or increase a taxable loss from the overall trade or business activity. Any disallowed amount due to the income limitation carries forward to the following tax year, where the same rules apply again.

For real estate, this limitation can be restrictive when the owner is not materially participating in business operations or when the activity is otherwise constrained.

Partnership and S corporation considerations

For partnerships and S corporations, both entity-level and owner-level limitations can apply. The Section 179 deduction passes through on Schedule K-1 and is subject to each owner’s income limitation and eligibility rules (including the trust/estate limitation described above).

Comparison to Bonus Depreciation Under Section 168(k)

There is significant overlap between the two primary federal provisions that can accelerate cost recovery: the Section 179 deduction and bonus depreciation under Section 168(k).

Eligibility differences matter

The four improvement categories listed above can be eligible for the Section 179 deduction. However, not all of those categories will qualify for bonus depreciation. Bonus depreciation generally applies to “qualified property,” which commonly includes property with a 20-year or shorter recovery period (along with certain other categories). Many building improvements are often treated as 39-year nonresidential real property unless a cost segregation analysis supports shorter-lived components, so bonus depreciation may not be available in many “roof/HVAC/security” improvement fact patterns even when Section 179 is available.

Qualified Improvement Property (QIP) is the main overlap

Beyond the four specific categories above, Qualified Improvement Property (QIP) also qualifies as Section 179 real property. QIP is generally an improvement to an interior portion of a nonresidential building already placed in service, provided the improvement is not:

• an enlargement of the building,
• an elevator or escalator, or
• an improvement to the internal structural framework of the building.
  

Under OBBBA and IRS guidance in Notice 2026-11, QIP can be eligible for 100% bonus depreciation if acquired after January 19, 2025 (assuming it otherwise meets Section 168(k) requirements). Notice 2026-11 also provides transition elections in certain circumstances (including the ability, in defined situations, to claim a reduced bonus percentage instead of 100%).

Key planning differences between Section 179 and bonus depreciation

• Dollar limitations: Section 179 has an annual cap and phaseout; bonus depreciation does not have the same annual dollar limitation.
• Income limitation: Section 179 generally cannot create or increase a loss; bonus depreciation can generally create or increase a net operating loss (NOL), subject to other limitations.
• Trust/estate eligibility: trusts and estates generally cannot claim Section 179, but they may be able to claim bonus depreciation if the property otherwise qualifies.
• Ordering: Section 179 is applied before bonus depreciation, and remaining basis is generally then recovered under MACRS.
• State conformity: Many states decouple from Section 179, bonus depreciation, or both. The state impact can materially change the overall result.
  

Other Factors to Consider

Section 179 recapture

If Section 179 property ceases to be used predominantly (more than 50%) in a trade or business before the end of its normal recovery period, the Section 179 benefit may be subject to recapture and reported as ordinary income in the year business use drops below the threshold. For real estate improvements used exclusively in a trade or business, this is often not an issue — but it should remain on the radar. This recapture rule does not apply to Bonus Depreciation.

State conformity

Many states decouple from the Section 179 deduction and/or bonus depreciation. Some states impose different phaseouts or limitations for Section 179, and some do not adopt federal bonus depreciation rules (including federal changes made under TCJA or OBBBA). Understanding the state impact is essential to evaluating the overall benefit.

Getting the Analysis Right

The Section 179 deduction is not a broad invitation to expense capital expenditures on demand. It is a precisely defined election with specific qualifying categories, phaseouts, income limitations, eligibility restrictions (including trusts and estates), and potential recapture exposure. Applied correctly, it can meaningfully accelerate tax benefits for legitimate improvement expenditures. Applied carelessly, it can result in an understatement of taxable income or create a filing position that is difficult to substantiate.

At Wiss, our real estate tax practice works with property owners to evaluate every available deduction — including the Section 179 deduction, bonus depreciation under Section 168(k), and related planning strategies — and structure the approach that fits the facts. If you’re planning improvements or trying to optimize the tax treatment of work you’ve already completed, contact our team for a consultation.

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