You just closed on a $220,000 excavator in March. Your CPA says something about “Section 179” at tax time, you nod, and that’s about it. Sound familiar?
Most construction business owners know Section 179 exists. Very few know how to actually use it — the forms, the timing, the traps that turn a six-figure write-off into an audit headache. This guide walks through the real process, with 2026 numbers that reflect the One Big Beautiful Bill Act changes.
For form and instructions, see IRS Form 4562 (Instructions).
The 2026 Numbers You Actually Need
Before making any purchase decisions, you need the confirmed limits. The tax landscape changed significantly with recent legislation.
The 2026 inflation-adjusted limits (see Revenue Procedure 2025-32):
- Maximum Section 179 deduction: $2,560,000
- Phase-out threshold: $4,090,000 in total equipment purchases
- Taxable income limit: Your deduction can’t exceed your net taxable business income (excess carries forward)
- SUV limit: $32,000 for heavy SUVs
Major change — Bonus Depreciation: The One Big Beautiful Bill Act (OBBBA) made 100% bonus depreciation permanent for qualified property acquired and placed in service after January 19, 2025. This supersedes the old TCJA phase-down schedule. See IRS bonus depreciation FAQ for details.
That phase-out is a dollar-for-dollar cliff. Buy $4,290,000 in equipment and your Section 179 deduction drops to $2,360,000. Buy $6,650,000 and it’s gone entirely. If you’re running a mid-size operation doing fleet upgrades, you can hit that ceiling faster than you think.
Verify these limits with your CPA and the linked IRS documents; state conformity can differ. See our state-by-state table below.
Step-by-Step: How to Actually Claim the Deduction
The mechanical process of claiming Section 179 is straightforward if you follow it in order. Here’s exactly what happens at filing time.
Step 1: Confirm the equipment qualifies
It must be tangible, depreciable property used more than 50% for business. For construction, that covers almost everything with an engine or a hydraulic system — but keep reading for the gray areas.
Step 2: Place it in service before December 31, 2026
Not purchased. Not delivered. Placed in service. More on this below because it’s where most contractors get burned.
Step 3: File IRS Form 4562 (Depreciation and Amortization)
This is the actual form. See sample filling instructions. Specifically:
- Part I, Line 6: Enter the total cost of Section 179 property placed in service.
- Part I, Line 12: Enter the total Section 179 expense deduction you’re claiming.
- Part I, Line 13: Carryover from prior years (if any).
- Part I, Line 21: The total deduction that flows to your tax return.
If you’re an S-corp or partnership, the election happens at the entity level on the business return, and the deduction passes through to your K-1. Sole proprietors file it on Schedule C via Form 4562.
Step 4: Elect the deduction — don’t assume it’s automatic
Section 179 is an election. You have to actively choose it on Form 4562. If you forget, the IRS defaults you to MACRS depreciation over 5 or 7 years (though bonus depreciation may still apply automatically). Election must be made on Form 4562 for the tax year in which property is placed in service; if omitted, file an amended return (see instructions for your business return).
Step 5: Keep the documentation airtight
Purchase invoices, delivery receipts, photos of the equipment on the job site with timestamps, and a log showing when it was first assigned to a project. The IRS doesn’t ask for this upfront. They ask for it during an audit, usually three years later, when you can’t find the paperwork.
What Qualifies (and What Doesn’t) in Construction
The IRS is fairly inclusive about what counts as qualifying equipment for construction businesses — but documentation requirements vary widely by asset type.
Clearly eligible:
- Excavators, dozers, skid steers, wheel loaders, backhoes
- Cranes (mobile and tower, if you own them)
- Concrete pumps, pavers, compactors
- Generators and light towers
- Heavy-duty trailers and lowboys
- Portable air compressors
Eligible but scrutinized — document heavily:
- Attachments. Hydraulic hammers, grapples, augers, thumbs. These qualify, but only if they’re invoiced separately or clearly itemized. An anonymized client example: a contractor in Texas lost a $34,000 deduction because his dealer bundled a hammer into the excavator invoice as “package pricing.” The IRS disallowed it. Get itemized invoices.
- Pickup trucks over 6,000 lbs GVWR. These fall under the heavy vehicle exception in IRS rules. If the truck’s gross vehicle weight rating exceeds 6,000 lbs and it’s used more than 50% for business, the full purchase price qualifies. This covers most F-250s, 2500s, and anything bigger. But if you use it for personal commuting, you need a mileage log that holds up under audit.
- Software embedded in equipment. GPS grading systems, machine control, telematics. These qualify if they’re integral to the equipment’s function. Standalone project management software does not.
Not eligible:
- Land and land improvements (grading, paving, fencing)
- Permanent structures (even a prefab office on your lot)
- Inventory or materials
- Equipment used 50% or less for business
The “Placed in Service” Deadline — Where Deductions Go to Die
This single rule causes more missed deductions than anything else in construction tax planning. Understanding the precise definition protects your write-off.
IRS defines “placed in service” in Publication 946 — see examples and documentation recommendations there. It means the equipment is ready and available for its specific use. Not sitting in the yard. Not waiting for an operator. Not waiting on a hydraulic fitting that’s backordered.
Real scenario (anonymized client example): A contractor in Ohio took delivery of a $380,000 dozer on December 22, 2025. It sat on the lot because the operator was on vacation until January 4. His CPA correctly told him the deduction belonged to 2026, not 2025. That’s a $380,000 deduction shifted by a full year because of a two-week vacation.
How do I prove placed-in-service status?
Your December checklist (with documentation notes for each item):
- Equipment physically delivered to your yard or job site — obtain signed delivery receipt with date and location.
- All setup, calibration, and safety inspections completed — retain service records or inspection certificates.
- Fuel in the tank, fluids checked — photograph fuel gauge and maintenance log entry.
- Assigned to a specific project or operator (even if the project starts in January) — note the project name and contract number in your equipment log.
- Dated photo on the job site or yard with a visible timestamp — use a camera or phone with GPS and date metadata enabled.
If you can check all five boxes by December 31, you’re in service. If you’re missing even one, you’re gambling.
Used Equipment: Both Section 179 and Bonus Depreciation Apply
The secondary market for heavy equipment offers massive tax advantages — and recent legislation made it even better.
Both Section 179 and bonus depreciation apply to used equipment, as long as it’s “new to you” and meets eligibility requirements. See Section 179 vs Bonus Depreciation comparison.
What counts as “used” property that qualifies?
Any equipment that has had a previous owner, regardless of age or hours. The IRS doesn’t care if it’s a 2018 model with 8,000 hours or a 2024 demo unit — if you didn’t buy it new from the manufacturer, it’s used for depreciation purposes.
Five requirements for used property to qualify for bonus depreciation (from IRS FAQ):
- Property was not used by you or a predecessor before acquisition
- Not acquired from a related party
- Your basis isn’t determined by the seller’s adjusted basis
- Not acquired from a decedent (sections 1014(a) or 1022)
- Cost doesn’t include basis of property you previously held
The math is stark. A 2022 Cat 336 excavator with 3,200 hours might cost $240,000 on the used market versus $420,000 new. With 100% bonus depreciation (or Section 179), you deduct the full $240,000 against this year’s income. Your after-tax cost drops to roughly $168,000 (assuming a 30% effective tax rate).
Used Equipment Calculation Example (2026 Rules)
| Item | Used Excavator | New Excavator (same class) |
|---|---|---|
| Purchase price | $240,000 | $420,000 |
| Section 179 deduction (2026) | $240,000 (100%) | $420,000 (100%) |
| Bonus depreciation (2026, if not using Section 179) | $240,000 (100%) | $420,000 (100%) |
| Tax savings at 30% rate | $72,000 | $126,000 |
| After-tax cost | $168,000 | $294,000 |
The used machine costs you $126,000 less after tax — for comparable work capacity.
The one trap: The related-party rule. You cannot claim Section 179 or bonus depreciation on equipment bought from a spouse, parent, child, sibling, or a corporation you control. Buying your brother’s backhoe doesn’t count. The IRS checks this, and it’s an automatic disallowance.
Section 179 vs. Bonus Depreciation in 2026: Understanding the Interplay
With 100% bonus depreciation now permanent, understanding how these two deductions work together is where real planning value lives.
| Feature | Section 179 | Bonus Depreciation (2026) |
|---|---|---|
| Max deduction | $2,560,000 | 100% (no dollar cap) |
| New equipment | ✅ | ✅ (100%) |
| Used equipment | ✅ | ✅ (100%, if “new to you”) |
| Income limitation | Yes — can’t exceed taxable income | No — can create a net operating loss |
| Phase-out | Yes, after $4.09M in purchases | No phase-out |
| Election required | Yes (Form 4562) | Automatic (must opt out if you don’t want it) |
Bonus depreciation is generally automatic unless you elect out; Section 179 requires election on Form 4562. Order matters — you can use Section 179 first to reduce the basis, then bonus depreciation applies to the remaining eligible basis. Document your rationale in tax workpapers.
3-Asset Scenario: Step-by-Step Calculation (2026 Rules)
Input: Used excavator $240,000; New dozer $350,000; New crane $900,000; Section 179 cap $2,560,000; Bonus depreciation 100%.
| Step | Action | Remaining Section 179 Cap |
|---|---|---|
| 1 | Apply Section 179 to used excavator: $240,000 | $2,560,000 − $240,000 = $2,320,000 |
| 2 | Apply Section 179 to new dozer: $350,000 | $2,320,000 − $350,000 = $1,970,000 |
| 3 | Apply Section 179 to crane: $900,000 (full amount) | $1,970,000 − $900,000 = $1,070,000 remaining |
| 4 | Total Section 179 deduction | $1,490,000 (all three assets fully covered) |
Result: Total first-year deduction = $1,490,000 on $1,490,000 of equipment (100% write-off).
With the higher Section 179 limit and 100% bonus depreciation, you can often write off your entire equipment purchase in year one — whether new or used.
The State Conformity Trap Nobody Talks About
How does state conformity affect my return? This is the issue that blindsides multi-state contractors every year. Federal deductions don’t automatically translate to state returns.
Federal Section 179 limits are not automatically adopted by states. Several major construction states decouple from the federal rules:
| State | Conforms to Federal Section 179? | Notable Rule/Cap | Source |
|---|---|---|---|
| California | No (cap applies) | California cap on Section 179: $25,000 (addback required on state return) | CA FTB |
| New Jersey | No (different phase-out) | NJ has its own depreciation rules; does not conform to federal bonus depreciation or expanded 179 limits | NJ Division of Taxation |
| New York | Partial (verify annual changes) | Generally conforms but has made mid-year legislative adjustments; check current-year guidance | NY Dept. of Taxation |
| Pennsylvania | No (separate tracking required) | PA requires separate depreciation schedules; does not conform to federal bonus depreciation | PA Dept. of Revenue |
| Texas | N/A | No state individual income tax — federal deduction applies without state adjustment | N/A |
| Florida | N/A | No state individual income tax — federal deduction applies without state adjustment | N/A |
| Ohio | Partial | Ohio has its own depreciation addback rules for certain entities; verify with current guidance | Ohio Dept. of Taxation |
| Illinois | Partial | Illinois decoupled from federal bonus depreciation; Section 179 conformity varies by year | IL Dept. of Revenue |
| Georgia | Yes (generally) | Georgia generally conforms to federal depreciation rules; verify annual updates | GA Dept. of Revenue |
| North Carolina | Partial | NC has decoupled from bonus depreciation in recent years; Section 179 rules may differ | NC Dept. of Revenue |
This table is a quick reference — always confirm with the state’s tax authority before filing, as conformity rules can change mid-year.
If your construction company operates across state lines — and most mid-size contractors do — you need a state-by-state depreciation schedule. Your CPA should be tracking this. If they’re not, you’re either overpaying state taxes or underpaying and setting yourself up for penalties.
The Recapture Problem: Selling Too Early Costs You
Section 179 comes with strings attached. If you dispose of equipment before the end of its recovery period, the IRS may claw back part of your deduction. Understanding recapture before you sell protects you from unpleasant surprises.
Section 179 comes with a five-year recapture window. If you sell or stop using the equipment for business before the end of year five, the IRS claws back a portion of the deduction as ordinary income. See Form 4797 instructions for the calculation method.
Recapture Calculation Example
| Year | Event | Amount |
|---|---|---|
| 2026 | Section 179 deduction claimed | $200,000 |
| 2028 (Year 3 of 5) | Equipment sold | — |
| — | Recapture percentage (approx. 40% for Year 3) | 40% × $200,000 = $80,000 |
| — | $80,000 added to taxable income as ordinary income | Tax hit at 30% rate: $24,000 |
The math: You deducted $200,000 on a loader in 2026. You sell it in 2028 (year three of five). The IRS recaptures roughly 40% of the deduction — $80,000 — added to your taxable income at ordinary rates, not capital gains. At a 30% marginal rate, that’s an unexpected $24,000 tax bill on top of any gain from the sale itself.
How to manage it:
- Don’t take Section 179 on equipment you plan to flip within 2–3 years. Use regular MACRS instead.
- If you must sell, try to time it for a year when your income is lower or you have offsetting losses.
- Trade-ins are treated differently than outright sales — the current trade-in rules for equipment can defer recapture. Talk to your CPA before you sign the deal.
How Section 179 Affects Your QBI Deduction
This is the interaction most articles completely miss, and it can cost you real money. The relationship between depreciation elections and the Qualified Business Income deduction is non-obvious but significant.
The Qualified Business Income deduction (Section 199A) lets eligible pass-through entities deduct up to 20% of qualified business income. But QBI is calculated after the Section 179 deduction.
Translation: A massive Section 179 write-off reduces your QBI, which reduces your 20% QBI deduction. In some cases, taking the full Section 179 deduction actually leaves you worse off than spreading the depreciation over two or three years.
When this matters most: If your taxable income is between $191,950 and $241,950 (single) or $383,900 and $483,900 (married filing jointly) — the QBI phase-in range for specified service trades — the interaction gets complex. Construction is generally not a specified service trade, so you’re usually fine, but the income reduction still shrinks your QBI base.
QBI Interaction: Two-Scenario Comparison
Note: This table is illustrative. Run full pro forma projections with your CPA before making decisions.
| Metric | Scenario A: Full Section 179 Now | Scenario B: Spread Depreciation ($100k 179 + MACRS) |
|---|---|---|
| Pretax business income | $600,000 | $600,000 |
| Section 179 deduction claimed | $300,000 | $100,000 |
| Other depreciation (MACRS) | $0 | $40,000 (Year 1 of 5-year schedule) |
| Total depreciation | $300,000 | $140,000 |
| Taxable income after depreciation | $300,000 | $460,000 |
| QBI base | $300,000 | $460,000 |
| QBI deduction (20%) | $60,000 | $92,000 |
| Net taxable income after QBI | $240,000 | $368,000 |
In Scenario A, you save $160,000 in current-year depreciation but lose $32,000 in QBI deduction. The net benefit depends on your marginal tax rate and future income expectations — which is why modeling both scenarios matters.
Lease vs. Buy: Does Section 179 Change the Equation?
The buy-versus-lease decision is already complex; adding Section 179 into the mix shifts the economics further in favor of ownership for many contractors.
If you’re leasing equipment through a capital lease (finance lease), the IRS treats it as a purchase for Section 179 purposes. You can claim the deduction on the present value of the lease payments.
Operating leases (true leases) don’t qualify. You deduct the lease payments as ordinary expenses, which is simpler but usually less advantageous for high-value equipment.
The 2026 calculation: With 100% bonus depreciation now permanent, buying has become even more attractive. If you have the cash flow and the taxable income to absorb the deduction, buying and taking Section 179 (or letting bonus depreciation apply automatically) is usually the stronger play for equipment you’ll keep longer than three years.
Your 2026 Action Plan
Timing and coordination with your CPA determine whether you capture the full benefit or leave money on the table. Here’s your calendar.
- October: Meet with your CPA. Bring your income projection, equipment wish list, and current fleet age report.
- November: Finalize purchase decisions. Order lead times on heavy equipment run 8–16 weeks. If you wait until December, you’re too late.
- December 15: Confirm delivery dates for all ordered equipment. Push dealers for year-end delivery if needed.
- December 31: Run the placed-in-service checklist on every new asset. Photograph everything.
- January–March (filing season): Review Form 4562 with your CPA before filing. Confirm the Section 179 election is checked, the amounts match your records, and state adjustments are calculated.
- Ongoing: Maintain a depreciation schedule that tracks federal and state separately. Update it every time you buy, sell, or trade equipment.
Frequently Asked Questions
What does “placed in service” mean for construction equipment?
The equipment must be ready and available for its intended use by December 31. Delivery alone isn’t enough — setup, fueling, and assignment to a project must be complete. See IRS Publication 946 for the official definition and examples.
Can I apply Section 179 to used equipment bought from a relative?
No. The related-party rule prohibits Section 179 deductions on purchases from spouses, parents, children, siblings, or entities you control. The equipment must be acquired from an unrelated third party.
Does bonus depreciation apply to used equipment in 2026?
Yes. Under the One Big Beautiful Bill Act, 100% bonus depreciation applies to both new and used equipment, as long as it’s “new to you” and meets the five eligibility requirements (not previously used by you, not from a related party, etc.).
How does recapture work if I sell equipment in year three?
Approximately 40% of the original Section 179 deduction is recaptured as ordinary income. This is reported on Form 4797. The recapture amount is added to your taxable income at ordinary rates, not capital gains rates.
Does federal Section 179 automatically apply to my state tax return?
No. Many states decouple from federal depreciation rules. California caps Section 179 at $25,000. New Jersey and Pennsylvania have their own depreciation systems. Check your state conformity table above and verify with your state’s tax authority.
Can Section 179 create a net operating loss?
No. Section 179 is limited to your taxable business income — any excess carries forward to future years. Bonus depreciation, by contrast, can create or increase a net operating loss.
Do I need to take Section 179 on all qualifying equipment?
No. You can elect Section 179 on specific assets and use MACRS depreciation (or let bonus depreciation apply) on others. This flexibility lets you optimize your deduction strategy based on income projections and asset lifecycle.
What if I forget to elect Section 179 on my original return?
You can file an amended return to make the election, but there are time limits and procedural requirements. See the instructions for Form 4562 for details on late elections.
Are pickup trucks eligible for Section 179?
Yes, if the truck’s gross vehicle weight rating (GVWR) exceeds 6,000 lbs and it’s used more than 50% for business. This includes most heavy-duty pickups (F-250, 2500 series, and larger). Maintain a mileage log to substantiate business use percentage.
What’s the difference between Section 179 and bonus depreciation in 2026?
Section 179 is an election with a $2.56M cap and income limitation; bonus depreciation is automatic at 100% with no cap or income limitation. Both apply to new and used equipment. You can use Section 179 first, then bonus depreciation applies to the remaining basis.
Does Section 179 reduce my QBI deduction?
Yes, indirectly. The QBI deduction is calculated on income after Section 179. A larger Section 179 deduction reduces your QBI base, which reduces your 20% QBI deduction. Model both scenarios with your CPA to determine the optimal strategy for your situation.
This guide reflects IRS rules as of the 2026 tax year, including Revenue Procedure 2025-32 and the One Big Beautiful Bill Act bonus depreciation provisions. Tax law changes frequently — verify specifics with a licensed CPA or tax attorney familiar with construction industry taxation.
