Section 179 expensing and bonus depreciation: how business equipment expensing actually works after TCJA

The combination of IRC §179 immediate expensing and IRC §168(k) bonus depreciation provides one of the most powerful tax-deferral tools available to small and mid-size businesses for capital equipment acquisition. The two provisions operate together but with substantially different rules, limitations, and phase-out schedules. The 2017 Tax Cuts and Jobs Act (TCJA) substantially expanded both provisions, but bonus depreciation is currently scheduled to sunset under the original TCJA phase-down schedule (100% bonus through 2022, 80% in 2023, 60% in 2024, 40% in 2025, 20% in 2026, and 0% from 2027 forward, absent legislative action to extend).

The substantive effect of these provisions is to convert what would otherwise be multi-year depreciation deductions into immediate first-year deductions. A business purchasing $500,000 of qualifying equipment under normal Modified Accelerated Cost Recovery System (MACRS) depreciation would deduct $500,000 spread over 5-7 years (depending on equipment classification). Under §179 or bonus depreciation, the same $500,000 can be deducted in the first year — substantially reducing current-year taxable income and creating substantial tax-deferral benefits. For a business in the 37% tax bracket, the first-year deduction creates approximately $185,000 of immediate tax savings on the $500,000 purchase, compared to spreading the same tax benefit over 5-7 years under normal depreciation.

The framework has substantial procedural and substantive requirements. The taxpayer must:

Use qualifying property (most business equipment qualifies; some real property qualifies for §179 only)
Place property in service during tax year (delivery alone insufficient)
Use property predominantly in trade or business (>50% business use minimum)
Make timely §179 election on the tax return
Stay within annual dollar limits
Address phase-out thresholds based on total qualifying purchases
Comply with various recapture provisions

This is how the §179 and bonus depreciation framework actually works post-TCJA, the substantive requirements for each provision, the strategic interaction between §179 and bonus depreciation, the phase-down schedule and planning considerations, and the strategic considerations for business owners using equipment expensing.

What §179 actually does

Under IRC §179(a):

"A taxpayer may elect to treat the cost of any section 179 property as an expense which is not chargeable to capital account. Any cost so treated shall be allowed as a deduction for the taxable year in which the section 179 property is placed in service."

Immediate expensing election. §179 allows taxpayer to:

Elect to deduct qualifying property cost in year placed in service
Convert capital asset into immediate expense
Avoid multi-year MACRS depreciation
Maintain election year by year (flexibility)

2024 limits (indexed annually):

Maximum §179 deduction: $1,160,000
Phase-out threshold: $2,890,000 of qualifying purchases
Above threshold: §179 deduction reduced dollar-for-dollar
Complete phase-out at $4,050,000 of qualifying purchases

2025 limits:

Maximum deduction: $1,220,000 (estimated, pending IRS adjustment)
Phase-out threshold: $3,050,000 (estimated)

Indexing. Per IRC §179(b):

Annual cost-of-living adjustments
IRS Revenue Procedure updates each year
Trend toward continued expansion

Taxable income limitation. Per IRC §179(b)(3):

§179 deduction cannot exceed aggregate trade or business taxable income
Disallowed amount carries forward indefinitely
Substantial limitation for small businesses with limited income
Important strategic consideration

Example calculation:

Business buys $1,500,000 of equipment in 2024
§179 elected on $1,160,000 (maximum)
$1,500,000 - $1,160,000 = $340,000 (remaining basis)
$340,000 available for bonus depreciation or MACRS
2024 bonus depreciation at 60%: $204,000 additional first-year
Total first-year deduction: $1,364,000
Remaining $136,000 depreciated under MACRS over 5-7 years

What §179 property includes

Per IRC §179(d) and Treas. Reg. §1.179-4:

Tangible personal property. Substantially all business equipment:

Machinery and tools
Office equipment (computers, printers, copiers)
Furniture and fixtures
Manufacturing equipment
Construction equipment
Agricultural equipment
Restaurant equipment

Off-the-shelf computer software. Substantial inclusion:

Most pre-packaged software
Software with substantial use period

Certain real property improvements (TCJA expansion):

Qualified Improvement Property (QIP) — interior improvements to nonresidential property
Roofs
Heating, ventilation, air conditioning (HVAC)
Fire protection and alarm systems
Security systems

Vehicles. With substantial limitations:

Cars: Limited under "luxury auto" rules ($20,200 max in 2024 with bonus, $12,200 without)
Light trucks/SUVs >6,000 lbs gross weight: Substantially higher limits
Trucks >14,000 lbs: Full §179 available (no luxury auto limit)
Cargo vans: Generally full §179 available

SUV exception. SUVs between 6,000 and 14,000 lbs gross vehicle weight:

$30,500 §179 maximum (2024)
Limited compared to other property
"Heavy SUV" framework

Excluded property:

Real property (buildings, structures) except as noted above
Property used predominantly outside U.S.
Property used for lodging (some exceptions)
Property received from related persons
Property used in a passive activity
Equipment held in inventory

What bonus depreciation does

Under IRC §168(k):

Additional first-year depreciation deduction. Bonus depreciation provides:

Percentage of qualifying property cost deductible in first year
In addition to regular MACRS depreciation
Different from §179 (which is immediate expensing election)

TCJA bonus depreciation rates (sunset schedule):

2017 (post-TCJA enactment) - 2022: 100%
2023: 80%
2024: 60%
2025: 40%
2026: 20%
2027 and later: 0% (under current law)

Currently scheduled to sunset. Without legislative extension:

2026: 20% bonus
2027 forward: 0% bonus
Substantial planning consideration

Note: Various bills propose extending or restoring bonus depreciation. Monitor tax legislation for changes.

What qualifies for bonus depreciation

Per IRC §168(k)(2):

MACRS property with recovery period 20 years or less. Substantially:

Most tangible business property
Equipment, machinery, furniture
Computer software
Qualified Improvement Property (QIP)

Used property (TCJA expansion). Critical change from prior law:

Pre-TCJA: Only new property qualified for bonus
Post-TCJA: Used property qualifies if first use by taxpayer
Substantial planning opportunity for businesses buying used equipment

Excluded property:

Property used for residential rental
Property with longer than 20-year recovery period
Property required to use Alternative Depreciation System (ADS)
Property used in trade or business of furnishing or sale of regulated utilities

Qualified Improvement Property (QIP) interesting history:

Pre-CARES Act: Mistakenly excluded from 100% bonus due to drafting error
CARES Act (2020): Retroactively fixed to include QIP at 15-year recovery
Current treatment: 15-year recovery, eligible for bonus depreciation

§179 vs. bonus depreciation strategic differences

The two provisions have substantially different rules:

Limit structure

§179 limits:

$1,160,000 annual maximum (2024)
$2,890,000 phase-out threshold
Taxable income limitation
Indexed annually

Bonus depreciation limits:

No dollar limit
No phase-out threshold
No taxable income limitation (creates NOL if exceeds income)
Subject to TCJA sunset schedule

Election framework

§179 election:

Required to elect
Made on tax return
Property-by-property election possible
Can elect different amounts on different properties

Bonus depreciation:

Automatic (no election required to apply)
Election to OPT OUT available
Applied class by class (not property by property)
Default treatment

Income tax planning differences

§179 creates current-year income reduction only. Cannot:

Create a tax loss for tax year
Reduce other income below zero
Carry forward unused (but elected) §179 to future years
Suspended §179 deduction available in future years

Bonus depreciation creates current-year deduction even if generates loss. Can:

Create or increase Net Operating Loss
Reduce other income below zero
NOL carry-forward available (under current law, NOL carry-forward limited to 80% of taxable income in carry-forward year)
Substantial impact on multi-year planning

Recapture treatment

§179 recapture under IRC §1245:

Recapture if property converted to non-business use before fully depreciated
Recaptured as ordinary income
Substantial trap for early business changes
Watch for declining business use percentage

Bonus depreciation recapture:

Similar §1245 framework
Recapture upon sale, exchange, or conversion
Ordinary income on amount equal to depreciation deductions

State tax implications

State conformity varies substantially:

Full federal conformity states. Most states follow federal §179 and bonus depreciation:

Same federal limits and rules apply for state tax
Substantial state tax savings combined with federal

Partial conformity states. Some states:

Decoupled from federal bonus depreciation
May have own §179-equivalent provision
Different limits
Require adjustment to federal taxable income

No-conformity states. A few states:

Don't allow bonus depreciation
Have own depreciation systems
Require add-back of federal bonus on state return

Important states to watch:

California: Decoupled from federal bonus depreciation; has own §179-equivalent
New York: Decoupled in part
New Jersey: Decoupled in part
Pennsylvania: Decoupled in part
Various other states with specific rules

State tax planning considerations:

Multi-state businesses face complex calculations
Decoupling adjustments
Different state filing requirements
Substantial coordination required

Recapture provisions

Multiple recapture provisions apply:

§1245 recapture (general)

Under IRC §1245:

Sale or exchange of §1245 property. Triggers recapture:

Gain up to amount of depreciation (including §179 and bonus)
Recaptured as ordinary income
Substantial impact on equipment sales

Calculation:

Sale price - adjusted basis = gain
Gain up to depreciation deductions = ordinary income (recapture)
Excess gain = capital gain (rare for fully depreciated property)

§179 recapture for business use changes

Under Treas. Reg. §1.179-1(e):

Business use drop below 50% triggers recapture:

Property must remain >50% business use
Drop below 50% during recovery period triggers recapture
Recapture amount = §179 deduction less depreciation allowed if no §179 election

Common situations:

Personal use of business vehicle increasing
Reduced business activity making property unused
Conversion to personal use
Substantial trap for changing business circumstances

Listed property rules

Under IRC §280F:

"Listed property" subject to substantial restrictions:

Passenger automobiles
Property used for transportation
Property generally used for entertainment, recreation, amusement
Computers and peripherals (some exceptions)

Substantial business use requirement:

More than 50% business use required for §179 and bonus
Strict use tracking required
Substantial penalties for non-compliance
Recapture provisions apply

Vehicle-specific considerations

Vehicles have distinctive treatment:

Passenger automobiles

Substantial limitations. "Luxury auto" rules under IRC §280F:

2024 first-year limit: $20,200 (with bonus) or $12,200 (without bonus)
Lower limits for subsequent years
Substantial constraints on luxury vehicle deductions

Reduces incentive for high-end passenger automobiles as business deductions.

Heavy SUVs (6,000-14,000 lbs GVW)

Substantial §179 advantage:

$30,500 §179 maximum (2024)
Substantially higher than passenger autos
Substantial planning opportunity

Common heavy SUVs:

Cadillac Escalade
Chevrolet Suburban
Ford Expedition
GMC Yukon
Mercedes G-Class
Range Rover (some configurations)

Trucks >14,000 lbs GVW

Full §179 available. No luxury auto limit:

Heavy trucks
Box trucks
Commercial vehicles
Substantial deduction opportunity

Vans and cargo vehicles

Generally full §179 available:

Cargo vans
Commercial vans
Specialized vehicles
Pickup trucks with cargo capacity >6,000 lbs unloaded

Strategic considerations for business owners

For business owners using §179 and bonus depreciation:

Plan equipment purchases strategically. Timing matters:

December purchases (before year-end) qualify for current year
"Placed in service" required (not just purchased)
Equipment in business and ready for use
Substantial year-end planning opportunity

Use §179 before bonus depreciation typically. Strategic ordering:

§179 used first (annual limit applies)
Bonus depreciation on remainder
§179 limits more constraining
Maximize annual limit usage

Address the bonus depreciation phase-down strategically:

2024: 60% bonus
2025: 40% bonus
2026: 20% bonus
2027+: 0% (current law)
Accelerate purchases if possible
Monitor tax legislation for extensions

Watch the §179 taxable income limitation. Substantial limitation:

Cannot create loss with §179
Disallowed amounts carry forward
Substantial planning for limited-income years
May prefer bonus depreciation when §179 limitation would apply

Coordinate with pass-through entity choice:

Different entities have different §179 considerations
S-corp and partnership pass-through to owners
Owner-level taxable income limitation
Substantial complexity for multi-owner entities

Watch the §179 phase-out threshold. $2,890,000 (2024):

Large purchases reduce §179 amount
Pure dollar-for-dollar reduction
Bonus depreciation more useful at higher purchase levels

Address the §199A QBI deduction interaction:

Depreciation deductions reduce QBI
QBI deduction calculation affected
Substantial planning consideration

Plan for SE tax mechanics:

Depreciation reduces SE earnings
SE tax savings substantial
Combined with income tax savings creates substantial benefit

Coordinate with reasonable compensation analysis:

S-corp owners face reasonable compensation requirements
Depreciation doesn't reduce reasonable compensation
Substantial coordination required

Address business use tracking:

Maintain contemporaneous mileage logs (for vehicles)
Document substantial business use
Track personal use carefully
Listed property rules require strict compliance

Watch the §1031 like-kind exchange coordination:

Post-TCJA, §1031 limited to real estate
Equipment exchanges produce immediate gain
§1245 recapture applies to equipment sales
Substantial coordination with §1031 elimination for personal property

Plan state tax conformity. Multi-state considerations:

Federal expensing may not be state deduction
Decoupling adjustments
Different state §179 limits
Substantial compliance complexity

Address timing for newly-formed businesses:

§179 taxable income limitation
May benefit from bonus depreciation in early years
Substantial coordination with business start-up

Consider Qualified Improvement Property (QIP):

Interior improvements to nonresidential property
15-year recovery (post-CARES Act)
Eligible for bonus depreciation
Substantial real estate planning opportunity

Address heavy vehicle planning carefully:

$30,500 SUV maximum (2024)
Luxury auto rules for passenger vehicles
Heavy truck full deduction available
Substantial vehicle selection planning

Engage qualified tax professional for substantial purchases. Substantial purchases warrant:

Tax planning before purchase
Entity-level analysis
State tax coordination
Substantial benefit from professional planning

Plan for end-of-year purchases. December often substantial:

Equipment "placed in service" by December 31 qualifies for current year
Substantial year-end planning
Documentation of placed-in-service date
Substantial planning opportunity

Watch for accelerated depreciation legislation. Various bills proposed:

Extension of 100% bonus depreciation
Substantial monitoring required
Possible retroactive provisions
Substantial uncertainty in planning

Address LLC operating agreement considerations:

§179 allocation among members
Substantial allocation rules
Special allocations potentially available
Substantial coordination with operating agreement

Plan for Solo 401(k) and retirement contributions:

§179 reduces SE earnings
Retirement contribution limits depend on SE earnings
Substantial coordination required

Address tax debt planning coordination:

§179 deductions reduce current year tax
May affect IRS installment agreement calculations
Substantial coordination required for taxpayers with existing debt

Document the purchase comprehensively:

Invoice with date
Placed in service date
Business use percentage
Use logs (for vehicles)
Substantial substantiation requirements

Plan for asset disposition tax effects:

§1245 recapture on equipment sale
§1031 limited to real estate
Substantial coordination with §179/bonus
Equipment held to depreciation completion ideal

Coordinate with phantom equity and profits interests:

Equity arrangements may affect §179 allocation
Substantial coordination with capital arrangements
Operating agreement matters

Address the business succession planning integration:

Equipment values affect succession
§179 history affects basis
Substantial coordination required for transition planning

For business owners with substantial equipment purchase activity, the combination of §179 immediate expensing and §168(k) bonus depreciation provides substantial tax-deferral opportunities that can materially affect annual tax liability. The combined effect can convert substantial portions of capital expenditures from multi-year depreciation deductions into immediate first-year deductions, creating substantial current-year tax savings — particularly valuable for businesses in high tax brackets and businesses with substantial equipment investment cycles. The framework's complexity (§179 limits, bonus depreciation phase-down schedule, vehicle limitations, listed property rules, state conformity issues, recapture provisions) means that careful planning, qualified professional engagement, and strategic timing of equipment purchases can substantially affect long-term tax outcomes. The work for business owners is in engaging qualified tax counsel early in equipment acquisition planning, coordinating §179 elections with bonus depreciation strategy, tracking business use carefully for vehicles and listed property, watching state tax conformity issues, planning around the bonus depreciation phase-down schedule (currently scheduled to sunset by 2027), and addressing coordination with other tax planning provisions including §1031, QBI, and retirement contributions. For appropriate business owners, the framework provides substantial tax savings that justify careful planning investment, and the current phase-down schedule creates substantial near-term planning urgency that should drive equipment acquisition timing decisions during the transitional period.