Section 179 vs. Bonus Depreciation: Timing Purchases

Section 179 and bonus depreciation are both first-year expensing tools that let businesses deduct the cost of qualifying property immediately instead of depreciating it over several years. The core difference is control: Section 179 gives you asset-level choice and is capped at active business income, while bonus depreciation applies automatically to entire asset classes and can generate or deepen a net operating loss. For 2026, both provisions are permanent, and the spending limits are the highest they have ever been.

What Is Section 179 vs. Bonus Depreciation?

Section 179 (IRC §179)

Section 179 lets a business elect to expense the full cost of qualifying property in the year it is placed in service, up to an annual dollar limit. For 2026, that limit is $2,560,000, and it phases out dollar-for-dollar once total qualifying purchases exceed $4,090,000 (fully phased out at $6,650,000). The OBBBA raised the base limits to $2.5 million and $4 million (both indexed for inflation), making these figures permanent features of the code rather than temporary adjustments subject to Congressional renewal.

The deduction is capped at the taxpayer’s active business taxable income for the year. Any amount disallowed by that income cap carries forward indefinitely to future tax years, still subject to the income limitation each time it is used.

Bonus Depreciation (IRC §168(k))

Bonus depreciation, also called the additional first-year depreciation deduction, allows businesses to deduct a percentage of the cost of qualified property in the year it is placed in service. The OBBBA permanently restored the rate to 100% for qualified property acquired and placed in service on or after January 19, 2025. IRS Notice 2026-11 provides interim guidance taxpayers can rely on while Treasury finalizes proposed regulations.

Unlike Section 179, bonus depreciation has no dollar cap and no taxable income limitation. A business can claim more in bonus depreciation than it earned in a given year, creating or enlarging a net operating loss that may be carried forward under the NOL rules of IRC §172.

2026 Limits at a Glance

Feature	Section 179	Bonus Depreciation
2026 expensing rate	Up to 100%	100%
Annual dollar cap	$2,560,000	None
Phase-out threshold	$4,090,000 in purchases	None
Income limitation	Yes (active business income only)	No
Can create NOL	No	Yes
Asset-level election	Yes, property by property	No, applies by asset class
Election to opt out	Yes, per asset	Yes, per asset class
Carryforward if limited	Yes, indefinite	Not applicable

How Bonus Depreciation Changed Under the OBBBA

Before the One Big Beautiful Bill Act, bonus depreciation had been phasing down under the Tax Cuts and Jobs Act schedule: 80% in 2023, 60% in 2024, 40% in 2025, 20% in 2026. The OBBBA reversed that phase-down entirely. Property acquired and placed in service after January 19, 2025, qualifies for the full 100% rate regardless of when during the calendar year the asset is purchased, as long as both the acquisition and the in-service date fall after that cutoff.

One important timing rule: if a written binding contract for the property existed before January 20, 2025, the acquisition date is treated as the contract date, not the in-service date. That earlier date could push property outside the 100% window. Businesses reviewing pending capital commitments should confirm whether any pre-existing contracts affect eligibility.

The OBBBA also introduced a new category called qualified production property, which provides full expensing for certain building-level manufacturing facilities that would otherwise face a 39-year straight-line recovery period. This is a temporary provision with its own placed-in-service deadlines, not a permanent change.

Qualified Property: What Each Rule Covers

Section 179 Eligible Property

• Tangible personal property used more than 50% in an active trade or business (machinery, equipment, furniture, off-the-shelf software)
• Qualified improvement property (QIP): improvements to the interior of a nonresidential building after it is placed in service
• Certain listed property (subject to recordkeeping rules and the more-than-50% business-use test)
• Real property used for lodging in certain circumstances under the §179(f) election

Section 179 cannot be used for property held for passive investment, property used outside the United States, or property acquired from a related party in a non-arm’s-length transaction.

Bonus Depreciation Eligible Property

• Tangible property with a MACRS recovery period of 20 years or less (the same categories that qualify for Section 179, plus some additional ones)
• QIP (15-year recovery period, making it eligible)
• Used property, provided the taxpayer or a related party did not previously own the asset and it was acquired in an arm’s-length transaction
• Certain computer software and specified plants in farming businesses

Bonus depreciation does not apply to land, 27.5-year residential rental buildings as a whole, or 39-year commercial buildings as a whole (though QIP within those buildings qualifies).

The Income Limitation: Why It Matters for Planning

The taxable income cap is the most consequential practical difference between the two provisions. Section 179 is limited to the aggregate active business income of the taxpayer for the year. A sole proprietor, S-corp owner, or partner adds up the net income from all active trades or businesses in which they participate. If that sum is $400,000 and the Section 179 election would generate a $600,000 deduction, only $400,000 is deductible in the current year. The remaining $200,000 carries forward.

Bonus depreciation has no such restriction. A company purchasing $1 million of qualifying equipment in a break-even year can claim the full deduction, driving taxable income to a loss, and then carry that NOL forward at 80% of future taxable income under current law.

This distinction creates a clear planning principle: use Section 179 first when you have strong taxable income to absorb it and want to pick specific assets, then use bonus depreciation to capture remaining basis after the Section 179 election.

How the Two Provisions Interact

In practice, the two rules layer together rather than compete. The typical sequence:

1. Elect Section 179 on specific high-priority assets up to the income limit or the dollar cap, whichever is binding.
2. Bonus depreciation applies automatically to the remaining eligible basis of qualifying property (including remaining basis on any asset that received only partial Section 179 treatment), unless you affirmatively elect out.
3. Any remaining basis is depreciated under MACRS on the normal schedule.

The election-out rules differ between the two. For Section 179, the election is made (or revoked) at the asset level on Form 4562. For bonus depreciation, the opt-out election applies to an entire asset class (for example, all 5-year property placed in service during the year), meaning you cannot selectively apply bonus depreciation to one piece of equipment while excluding a different piece in the same class.

Depreciation Planning: When to Prefer One Over the Other

Favor Section 179 When:

• You have substantial active business income and want to reduce it to a specific target (for estimated tax or year-end planning)
• You want to cherry-pick which assets to deduct fully and which to depreciate normally
• You have prior-year Section 179 carryforwards and want to layer new elections carefully
• The business has owners who need pass-through income to stay within QBI deduction thresholds under IRC §199A

Favor Bonus Depreciation When:

• The business is in a high-growth, lower-income year and can benefit from an NOL carryforward
• Total equipment purchases exceed the Section 179 phase-out threshold ($4,090,000) and the dollar limit cap is binding
• You want to write off used equipment acquired in an arm’s-length purchase without an asset-by-asset election process
• The transaction involves qualified production property or qualified sound recording productions that only qualify under the OBBBA-specific bonus depreciation rules

Consider Both Together When:

• Year-end planning reveals a taxable income target and you want to reduce liability precisely: apply Section 179 to the extent income allows, then let bonus depreciation handle the rest
• A significant capital year (new facility buildout, fleet replacement) triggers purchases above the Section 179 phase-out threshold, making bonus depreciation the primary tool for new assets while Section 179 is reserved for specific high-basis equipment

For businesses working with Modus on strategic tax planning, modeling both scenarios in the same projection is routine, particularly for fiscal years ending mid-calendar year where asset purchase timing can shift income across periods.

Vehicle and Listed Property Rules

Passenger automobiles remain subject to the luxury auto limitations of IRC §280F regardless of which provision you use. For 2026, the IRS annually adjusts these caps via revenue procedure. Listed property more generally (vehicles, certain computers, recording equipment) requires a business-use percentage above 50% to qualify for either Section 179 or bonus depreciation. If business use drops to 50% or below in a later year, recapture rules apply.

Certain heavy SUVs with a gross vehicle weight rating between 6,001 and 14,000 pounds are subject to a separate Section 179 sub-limit. For 2026, that sub-limit is $32,000 under Rev. Proc. 2025-32, and it is indexed for inflation. This cap applies only to the Section 179 deduction. Any basis above the $32,000 ceiling can still be absorbed by 100% bonus depreciation, since the heavy SUV cap does not apply to bonus depreciation.

State Tax Conformity Considerations

Not every state follows federal bonus depreciation or Section 179 rules. Some states decouple from bonus depreciation entirely or cap Section 179 at a much lower amount. A business operating in multiple states may generate a large federal deduction but face very different state tax outcomes. State-level depreciation planning should be part of any capital expenditure review. Modus’s advisory team can model multi-state impacts alongside federal projections.

Related reading: 179D Deduction and 45L Tax Credit: What You Need to Know

Frequently Asked Questions

What is the difference between Section 179 and bonus depreciation?

Section 179 is an elective provision that lets businesses expense qualifying assets up to a capped dollar amount, limited by active business income. Bonus depreciation is automatic (unless elected out) and has no dollar cap or income limitation, and can create or expand a net operating loss. Both currently allow 100% first-year expensing on eligible property in 2026.

Can a business use both Section 179 and bonus depreciation in the same year?

Yes. The most common approach is to apply Section 179 first on selected assets up to the income limit, then let bonus depreciation automatically apply to any remaining eligible basis on qualifying property in the same year.

Does bonus depreciation apply to used equipment?

Yes, as long as the equipment is new to the taxpayer, was acquired in an arm’s-length transaction, and was not previously used by the taxpayer or a related party. Both new and used property can qualify for 100% bonus depreciation in 2026.

What is the Section 179 limit for 2026?

The Section 179 deduction limit for 2026 is $2,560,000. The deduction phases out dollar-for-dollar once total qualifying purchases for the year exceed $4,090,000 and is fully eliminated at $6,650,000.

Can bonus depreciation create a tax loss?

Yes. Because bonus depreciation has no taxable income limitation, a business can claim more depreciation than it has taxable income, creating a net operating loss. That NOL generally carries forward and offsets up to 80% of future taxable income per year under IRC §172.

Are buildings eligible for bonus depreciation?

Structural components of a building with a 39-year (commercial) or 27.5-year (residential) MACRS life are generally not eligible. However, qualified improvement property (interior improvements to a nonresidential building, 15-year life) does qualify. The OBBBA also created a temporary provision for certain qualified production property (manufacturing facilities), but that category has specific eligibility rules and phase-out dates.