Section 179 and bonus depreciation are two of the most widely used tools in small business tax planning. Under ordinary depreciation rules, a business that buys equipment, vehicles, or other qualifying property deducts the cost gradually over 3 to 7 years (or longer, for buildings and land improvements). Section 179 and bonus depreciation accelerate that deduction: a $50,000 piece of equipment can often be deducted entirely in the year of purchase rather than spread across multiple years. For a profitable business, this can reduce taxable income by tens or even hundreds of thousands of dollars in a single year.
The two provisions overlap and interact in ways that confuse many owners. Section 179 has dollar caps, income limits, and specific eligibility rules. Bonus depreciation has no dollar cap but is phasing down under current law (100% in 2022, dropping to 40% in 2025, 20% in 2026, and scheduled to expire in 2027 unless Congress extends it). Using both together in the right order typically produces the best result, but the specific choice depends on business income, planned future purchases, and state tax treatment, which often differs from federal.
Section 179 vs. Bonus Depreciation
Both accelerate deductions, but with different rules, caps, and applications.
| Feature | Section 179 | Bonus Depreciation |
|---|---|---|
| Annual Dollar Cap | $1.25M (2025), phase-out at $3.13M | No cap |
| Income Limitation | Cannot create a loss | Can create a loss |
| Property Eligibility | New or used; tangible personal property, certain real improvements | New or used; most business property with recovery period ≤ 20 years |
| Percentage | 100% of cost (up to cap) | 40% in 2025, 20% in 2026, expiring 2027 under current law |
| State Conformity | Most states conform | Many states decouple |
| Election Flexibility | Selected per asset; can elect out | Applies automatically unless elected out |
When to Use Section 179
Section 179 is typically the first-choice deduction for most small business purchases.
The Core Benefit
Deduct up to $1.25M of qualifying property in the year placed in service, rather than depreciating over 5-7 years. For a business buying $200K of equipment with 7-year recovery, Section 179 produces roughly $200K immediate deduction vs. ~$28K under straight-line depreciation, a major timing advantage.
Qualifying Property
Tangible personal property used more than 50% for business (equipment, machinery, furniture, most vehicles), off-the-shelf computer software, qualified improvement property (certain interior improvements to non-residential real estate), and some roofs, HVAC, fire protection, and security systems on commercial real estate.
The Income Limitation
Section 179 deduction cannot exceed taxable business income from the year. If you have $100K of business income, your Section 179 deduction cannot exceed $100K. Excess carries forward to future years. This contrasts with bonus depreciation, which can create a loss and produce net operating loss carryforwards.
The Phaseout
Dollar-for-dollar reduction in Section 179 limit once qualifying purchases exceed $3.13M (2025). A business purchasing $3.5M of qualifying property would see Section 179 limited to $880K ($1.25M - $370K excess). Above $4.38M of purchases, Section 179 is fully phased out, making bonus depreciation the only acceleration option.
When to Use Bonus Depreciation
Bonus depreciation applies when Section 179 doesn't fit or when larger-scale deductions are needed.
Under current law, bonus depreciation is phasing down: 60% in 2024, 40% in 2025, 20% in 2026, and 0% in 2027 and beyond. Each year's rate applies to property placed in service during that year. Businesses with major capital purchases in 2025-2026 face a meaningful planning decision: accelerate into 2025 to capture the 40% bonus, or wait and use Section 179 alone. Congress has repeatedly extended or modified bonus depreciation; monitor legislative developments as planning windows close. For property placed in service in 2025, the first-year deduction calculation is: Section 179 (up to $1.25M) applied first, then 40% bonus depreciation on remaining basis, then regular MACRS depreciation on the rest. Order matters.
Heavy Vehicles and the Depreciation Puzzle
Business vehicles have their own rules that interact with Section 179 and bonus depreciation.
Passenger Vehicles (Under 6,000 lbs GVWR)
- Luxury auto depreciation caps apply, limit year-one deduction regardless of Section 179
- 2025 first-year cap: ~$20,200 with bonus depreciation
- Section 179 capped at $12,200 for passenger autos
- Remaining basis depreciated over 5 years subject to annual caps
- Less aggressive year-one deduction possible
Heavy SUVs/Trucks (Over 6,000 lbs GVWR)
- Exempt from luxury auto caps
- SUV-specific Section 179 cap: $30,500 in 2025
- Pickups with 6+ foot beds often qualify for full $1.25M Section 179 cap
- Bonus depreciation (40% in 2025) applies on top
- Potential year-one deduction on a $70K heavy truck: $30K+ under Section 179 + bonus on remainder
Planning with Section 179 and Bonus Together
The optimal use of both provisions depends on the specific tax situation.
- Project current-year taxable income before depreciation decisions
- Identify all qualifying purchases and their placed-in-service dates
- Consider whether to elect out of bonus on specific assets (to preserve future depreciation)
- Check state tax treatment, many states don't conform to bonus depreciation
- Evaluate whether acceleration creates a loss, if so, bonus depreciation may be preferred over Section 179
- Assess future purchase plans, using depreciation aggressively this year means less available next year
- Consider QBI deduction interaction, heavy depreciation reduces QBI base
- Document purchase dates, placed-in-service dates, and business-use percentages
Section 179 and bonus depreciation are powerful timing tools, not permanent tax savings, they shift deductions into the current year rather than creating new ones. Used well, they smooth taxable income across years, front-load deductions into high-income years, and match depreciation to cash flow needs. Used poorly, they waste deductions (accelerating them in low-income years when they're worth less), trigger recapture later, or create mismatches with state tax. For most profitable small businesses, using Section 179 first up to its limit, then bonus depreciation on the remaining basis of qualifying property, produces the best result, but always after running the specific numbers for your situation and your state.
Time equipment purchases around taxable income, not tax year. A business with a profitable Q1-Q3 and a slow Q4 may benefit from accelerating a planned Q1 purchase into December to capture deductions against current-year income. Conversely, a business with a slow current year and a strong pipeline may want to elect out of bonus depreciation to preserve deductions for next year. The depreciation election is a timing lever, use it deliberately with your CPA, not reflexively.
Frequently Asked Questions
Yes. Section 179 applies to both new and used property, as long as it's new to your business. Buying a used piece of equipment from another company qualifies; moving an existing asset from personal to business use generally doesn't qualify for Section 179.
Depreciation recapture applies. The portion previously deducted (including Section 179 and bonus) is recaptured as ordinary income at sale, up to the gain. This is why depreciation timing matters: aggressive current-year deductions create larger recapture on future sales. For assets held long-term and worn out before sale, recapture is typically modest.
Partially. Land and buildings themselves don't qualify for Section 179. However, "qualified improvement property" (certain interior non-structural improvements to non-residential buildings) is eligible. Roofs, HVAC, fire protection, alarm systems, and security systems in commercial real estate are also Section 179-eligible under specific rules. Structural improvements to the building envelope generally are not.
Sometimes less is more. A business expecting higher tax rates in future years (due to higher income, QBI deduction phaseout, or state tax changes) may prefer to defer deductions. Electing out of bonus depreciation (asset-by-asset or by class) leaves the deduction for regular MACRS recovery, spreading it over 5-7 years when the tax savings may be worth more.
Sources
- SMAART Company. Small Business Depreciation Frameworks, 2026.
- Internal Revenue Service. Publication 946, How To Depreciate Property, 2025. irs.gov
- Internal Revenue Code Sections 168(k) and 179, 2025.
- American Institute of Certified Public Accountants. Depreciation Planning for Small Business, 2025. aicpa.org
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