Section 179 vs Bonus Depreciation for Real Estate Investors

Section 179 and bonus depreciation are the two main ways to write off a property-related asset in the year you buy it — but they work very differently. Bonus depreciation lets you deduct 100% of qualifying property in the first year with no dollar cap and no income limit. Section 179 lets you expense up to $2.56 million in 2026, but it's capped by your taxable business income and must be elected on your return. Talk to your CPA before choosing, because the income-limitation rule on Section 179 trips up more landlords than any other provision.

What Is Section 179?

Section 179 of the tax code lets a business expense the cost of qualifying property in the year it's placed in service, instead of depreciating it over several years. The One Big Beautiful Bill Act (OBBBA), signed July 4, 2025, made the higher limits permanent: for 2026, you can expense up to $2,560,000, and the limit phases out dollar-for-dollar once your total qualifying purchases exceed $4,090,000 — disappearing entirely around $6,650,000. Both figures adjust for inflation each year.

Eligible property includes machinery, equipment, software, qualified improvement property (QIP — interior improvements to nonresidential buildings), and certain improvements to nonresidential real property: roofs, HVAC, fire protection and alarm, and security systems. Residential rental buildings themselves are not Section 179 property.

Three hard rules govern Section 179:

You must elect it. Unlike bonus depreciation, Section 179 isn't automatic — you claim it on Form 4562 with your return.

It's limited to taxable income from your active trade or business. Section 179 cannot create a net loss. Any excess carries forward to future years, but you can't use it to push current-year income below zero.

The property must be placed in service by December 31. Merely ordering or paying for equipment isn't enough — it has to be ready and available for its intended use.

What Is Bonus Depreciation?

Bonus depreciation (§168(k)) is the first-year deduction for qualifying property with a recovery period of 20 years or less. Under OBBBA, 100% bonus depreciation is permanent for property acquired after January 19, 2025 (IRS Notice 2026-11), and it applies to both new and used property (as long as it's new to you).

Bonus differs from Section 179 in three important ways: it applies automatically unless you elect out; it has no dollar cap — a $20 million equipment purchase can be fully written off in year one; and it has no income limitation — bonus depreciation can create a net operating loss.

This is where cost segregation connects directly to bonus depreciation. A cost segregation study reclassifies portions of a building into 5-, 7-, and 15-year property — personal property, land improvements, and qualified improvements — and all of those classifications qualify for 100% bonus. The 27.5-year residential and 39-year nonresidential building shells themselves never qualify for bonus, which is why reclassification is the lever.

Section 179 vs Bonus Depreciation: The Comparison

When both apply to the same asset, IRS rules require you to apply Section 179 first, then take bonus depreciation on the remaining basis.

A Worked Example: The Income Limit in Action

Say an investor buys a $800,000 duplex and, through a cost segregation study, reclassifies $160,000 of it into 5-, 7-, and 15-year property. The investor also runs a small property management business that earns $90,000 of taxable income this year.

Bonus depreciation path: the full $160,000 of reclassified components gets 100% bonus depreciation in year one — regardless of the investor's income. The remaining $640,000 building shell depreciates over 27.5 years (about $23,273/year). Total first-year deduction: roughly $183,273. Section 179 path on the building components: personal property components could qualify for Section 179, but the deduction is capped at the investor's active business income. If the rental is a passive activity (as it is for most landlords), the investor may have only that $90,000 of business income to absorb the deduction — and any excess carries forward rather than offsetting this year's rental income. In practice, bonus depreciation is the cleaner tool for real estate components, because it has no income ceiling and no election paperwork.

Now flip it: the same investor buys $200,000 of trucks and equipment for the management business, with $1.2 million of business income. Section 179 works perfectly here — expense the full $200,000, well under the $2.56 million cap. When your income is high and purchases fit under the cap, either tool gets you to 100% in year one; Section 179 is often preferred because it's targeted — you can expense some assets and depreciate others, while bonus applies to an entire asset class per year unless you elect out.

When Should a Real Estate Investor Use Each?

Reach for bonus depreciation when:

• You own rental property and ran a cost segregation study — the reclassified 5/7/15-year components are bonus-eligible with no income limit. This is the bread-and-butter scenario.
• You're buying large amounts of equipment (over $4.09 million) — bonus has no cap.
• Your taxable business income is low or zero this year — bonus creates the deduction anyway.
• You acquired a property in a prior year and missed the deductions — a look-back cost segregation study with Form 3115 catches up past depreciation, and bonus applies to the catch-up.

Reach for Section 179 when:

• You're expensing active-business assets (vehicles, management software, office equipment) and have enough business income to absorb them.
• You want precision — Section 179 lets you expense specific assets while depreciating others; bonus is all-or-nothing per asset class per year.
• You want to avoid creating a loss — because Section 179 can't take you below zero, it won't generate an NOL you can't use.

Two Traps Landlords Fall Into

Trap 1: Assuming the building qualifies. Neither provision applies to the 27.5-year residential or 39-year nonresidential building shell. Landlords who "take Section 179" on a rental building have misapplied the law — only reclassified components qualify. If you've never had a cost segregation study done, most of your building isn't eligible for either first-year provision. Trap 2: Section 179 against passive rental income. Section 179 is limited to income from the active conduct of a trade or business. Rental real estate is generally a passive activity, so most landlords can't use Section 179 to shelter rental income — the deduction gets limited or carried forward while the depreciation they could have taken through bonus goes unclaimed. Bonus depreciation has no such restriction, which is why it's the workhorse for real estate.

One more planning note: both provisions accelerate deductions, and accelerated deductions eventually come back as depreciation recapture when you sell. A 1031 exchange or long hold can defer or reshape that bill.

The Bottom Line

For most real estate investors, bonus depreciation is the default tool: permanent at 100% for property acquired after January 19, 2025, uncapped, automatic, and — through cost segregation — applicable to a meaningful slice of every rental property. Section 179 is the precision tool: capped at $2.56 million in 2026 and limited to active business income, but ideal for equipment and targeted elections. Use them in the IRS-mandated order (Section 179 first, bonus on the rest), and run the combination past your CPA.

Want to know how much of your property qualifies for 100% bonus depreciation? A room42.io cost segregation study reclassifies your building into bonus-eligible components for a flat $525 per unit — get your free estimate and see your first-year deductions before you file.