100% bonus depreciation and the $2.5M Section 179: time big purchases before year-end
Two deductions now let most businesses write off the full cost of equipment in the year they buy it — instead of over five, seven or more years. The catch that trips people up isn't eligibility. It's timing. Here's how the tools work, how to combine them, and the deadline that decides your deduction.
For most of the last few years, "immediate expensing" was quietly dying. The 100% bonus depreciation created by the 2017 tax law was phasing down — 80% in 2023, 60% in 2024, and just 40% for 2025 — on its way to zero. Then the One Big Beautiful Bill Act reversed course.
Two separate provisions now let you deduct big capital purchases up front:
- 100% bonus depreciation (IRC §168(k)) is restored and made permanent for qualified property acquired and placed in service after January 19, 2025 — with no scheduled phase-down.
- Section 179 expensing was more than doubled: the annual cap jumped to $2.5 million for 2025 ($2,560,000 for 2026), with the phase-out threshold rising to $4 million ($4,090,000 for 2026).
Together, they mean a business buying equipment, machinery, vehicles, or interior build-outs can often deduct the entire cost in year one. But that deduction only lands in a given tax year if the asset is placed in service by December 31 — which is why year-end timing is the whole game.
Section 179 vs. bonus depreciation: they're not the same
People use these terms interchangeably, but they're two different tools with different rules. The differences decide the smartest way to combine them.
| Feature | Section 179 | 100% Bonus (§168(k)) |
|---|---|---|
| Annual dollar cap | $2.5M (2025) / $2.56M (2026) | None |
| Phases out above spending | Yes — above $4M / $4.09M | No |
| Limited by taxable income? | Yes (excess carries forward) | No — can create a loss |
| How you elect | Asset by asset | By asset class (elect out) |
| New & used property | Yes | Yes (if new to you) |
| Roofs, HVAC, fire & security systems | Yes | Generally no |
| Off-the-shelf software | Yes | Yes |
| State conformity | More states conform | Many states decouple |
The usual playbook: apply Section 179 first (you can pick exactly which assets and how much), then let 100% bonus depreciation sweep up the remaining basis. Because bonus has no income limit, it can carry a deduction past your current profit and create a net operating loss you carry forward.
Estimate your first-year write-off
Enter what you're buying and the calculator applies the Section 179 cap and phase-out for the year, layers on 100% bonus depreciation, and estimates your tax saving.
Why "placed in service" — not "paid for" — is the deadline that matters
The deduction attaches to the year an asset is placed in service: ready and available for its intended use in your business. Ordering it, paying for it, or even taking delivery isn't enough on its own — a machine still in its crate on December 31 generally hasn't been placed in service.
So if you want the write-off on this year's return, the practical deadline is getting the asset installed, connected, and genuinely usable before December 31 — not just purchased.
A worked example
First-year deduction: $150,000 · Estimated federal tax saving: $52,500 ($150,000 × 35%).
Spread over a typical seven-year schedule instead, that same purchase might have produced only a few thousand dollars of deduction in year one. That timing difference is the entire value of these provisions — the cash stays in your business now.
What property actually qualifies?
Bonus depreciation (§168(k)) generally covers tangible property with a recovery period of 20 years or less — machinery, equipment, computers, furniture, vehicles — plus off-the-shelf software and qualified improvement property (QIP, i.e. interior build-outs of nonresidential buildings). Used property qualifies too, as long as it wasn't previously used by you and is bought in an arm's-length purchase.
Section 179 covers the same equipment, and reaches some things bonus generally doesn't: roofs, HVAC, fire-protection and security systems installed on nonresidential real property. That's why 179 still matters even with 100% bonus available.
Vehicles have their own rules
Business vehicles can qualify, but "listed property" and luxury-auto limits (§280F) cap the write-off on lighter passenger vehicles. Heavy SUVs (gross vehicle weight roughly 6,000–14,000 lbs) have a separate Section 179 cap — $32,000 for 2026 — with any remaining basis eligible for bonus depreciation. Business-use percentage matters, and personal use reduces the deduction. Vehicles are a common audit area, so document business use carefully.
Building a factory? Section 168(n) may let you expense the building itself
The OBBBA added a new provision, §168(n), for qualified production property — certain new domestic nonresidential real property used in manufacturing, production or refining of tangible goods. Where it applies, you can expense 100% of the building's cost in year one instead of depreciating it over 39 years, subject to a defined construction-start window and a requirement to be placed in service before January 1, 2031. The rules are detailed and timing-sensitive, so this one genuinely needs a professional to structure before you build or retrofit.
Don't forget the states
These are federal rules. Many states decouple from bonus depreciation entirely and some limit Section 179, requiring you to add the deduction back for state purposes and depreciate over time on your state return. Because more states conform to Section 179 than to bonus, the 179-versus-bonus split can change your state result even when the federal total is identical. If you operate in multiple states, model this before year-end.
Faster isn't always smarter
Immediate expensing is powerful, but it isn't automatically the right call. A few situations where slowing down can beat speeding up:
- You expect higher tax rates later. A deduction is worth more in a high-bracket year. If your income (or rates) will climb, spreading depreciation forward may save more overall.
- You're in a low-income or loss year. Writing everything off against little income can waste deductions or bury them in an NOL you can't use soon.
- Watch depreciation recapture. If you sell the asset later, the depreciation you took is generally recaptured as ordinary income — so full expensing can shift, not erase, the tax.
- Financed purchases still count. You can deduct the full cost even if you financed it — a real cash-flow win — but make sure the debt service fits your plan.
Your year-end checklist
- Place assets in service by December 31 — installed, connected and usable, not just ordered.
- Confirm the acquisition date for anything contracted around January 2025, to know whether you're at 100% or the 40% legacy rate.
- Model 179 vs. bonus for your entity and your states — the split affects carryforwards and state tax.
- Match the deduction to a high-income year where possible, rather than reflexively taking it all now.
- Keep records: invoices, in-service dates, and business-use logs for vehicles. File it all on Form 4562.