§179 Expensing: OBBBA Permanent Doubling

Section 179 of the Internal Revenue Code allows a business to immediately deduct the full cost of qualifying property in the year placed in service rather than depreciating it over years. OBBBA doubled the baseline limits and made them permanent: $2,500,000 deduction cap with $4,000,000 phaseout threshold effective for property placed in service in tax years beginning after December 31, 2024, indexed for inflation thereafter. For 2026, the inflation-adjusted amounts are $2,560,000 cap and $4,090,000 phaseout, with full phase-out at $6,650,000 of qualifying purchases. The heavy SUV cap is $32,000 for 2026. Section 179 must be applied BEFORE bonus depreciation under IRS ordering rules. Section 179 cannot create a net loss (the business income limitation under §179(b)(3)). For interaction with §163(j) interest expense limitation, §179 amounts are treated as amortization, not depreciation.

How §179 Works - Three Limitations

Qualifying Property - §179(d)

Heavy Vehicle Rules - §179(b)(5)

The Ordering Rule - §179 BEFORE Bonus

IRS regulations and Form 4562 instructions establish a strict ordering: Section 179 expensing is applied first, then bonus depreciation under §168(k), then MACRS depreciation on what remains.

The Business Income Limitation - §179(b)(3)

Section 179 cannot create or increase a net operating loss. The deduction is capped by the aggregate taxable income from the active conduct of any trade or business. Excess that cannot be used in the current year carries forward indefinitely under §179(b)(3)(B).

The Spouse Aggregation Trap

Married couples filing jointly aggregate both spouses' business income for the §179 income limit. A spouse with W-2 wages from active employment plus a spouse with Schedule C self-employment combine their business income figures. This is favorable when one spouse has loss and another has wages.

Pass-Through Entity Mechanics - §179(d)(8)

Partnerships and S-corporations elect §179 at the entity level on the entity return (Form 1065 or Form 1120-S). The elected §179 amount passes through on Schedule K-1 to partners and shareholders. The DOLLAR CAP is then applied at the partner/shareholder level - meaning §179 from multiple K-1s plus a Schedule C business is all combined for purposes of the $2,560,000 (2026) individual cap.

§163(j) Interaction - §179 as Amortization

For purposes of the §163(j) business interest expense limitation, §179 deductions are treated as AMORTIZATION rather than DEPRECIATION. This matters for the "adjusted taxable income" calculation:

The Election Mechanics - Form 4562 Part I

State Conformity - The Single Biggest Practitioner Pitfall

Federal §179 election doesn't automatically apply at state level. States vary widely:

Common Practitioner Errors

Forgetting the 50% Business Use Threshold

Property used 50% or less for business does NOT qualify for §179. A vehicle used 49% for business produces zero §179 deduction - even though the same vehicle at 51% business use produces a deduction proportional to business use. The threshold is binary.

Treating Real Property Improvements as §179

Only Qualified Improvement Property (interior nonresidential improvements) plus enumerated systems (roofs, HVAC, fire protection, alarm, security) qualify for §179 on real property. Exterior building costs, new construction, residential improvements, and structural framework do NOT qualify. The 2017 TCJA expanded §179(f) but did not open the door to general real property §179.

Missing the Asset-by-Asset Election Opportunity

§179 is elected per asset. A taxpayer can §179 a $30,000 HVAC unit (eligible for §179, doesn't qualify for 100% bonus on certain real property structural integrations) while taking bonus depreciation on other equipment. Software defaults often apply §179 to all assets or none - manual review captures more deduction.

Skipping the Schedule C Spouse Income

For MFJ couples, the business income limit aggregates both spouses' active T/B income. A spouse with W-2 wages from active employment increases the §179 income limit. Missing this aggregation results in unnecessary carryforward of §179.

Treating §179 Carryforward as Use-Anytime

§179 carryforward is subject to the same business income limit in each succeeding year. A carryforward sits idle until the taxpayer has sufficient T/B income to absorb it. The carryforward also adds to the current-year §179 election for cap and phaseout testing.

Using §179 in Loss Years

If the business has a loss, §179 cannot be elected (would create / increase the loss). Better strategy: use 100% bonus depreciation (no income limit) to expense the property, creating a net operating loss that carries forward. Software sometimes applies §179 automatically even at a loss - manual override needed.

Missing Heavy SUV vs. Heavy Truck Distinction

A heavy SUV (6,000-14,000 lbs GVWR, passenger seating without 6'+ cargo bed) is capped at $32,000 §179 for 2026. A heavy pickup truck (6,000+ lbs GVWR, cargo bed 6'+ behind driver) has NO SUV cap - full §179 available. Examples that escape the SUV cap: F-250/F-350 long bed, RAM 2500/3500, full-size cargo vans, work vans. Examples that hit the SUV cap: Cadillac Escalade, Chevrolet Tahoe, Range Rover, large SUVs.

Ignoring State Decoupling

Many states cap §179 below federal or eliminate it entirely. California, New Jersey, Pennsylvania, Minnesota historically have had material differences. Failing to compute separate state depreciation produces wrong state taxable income for years.

Election on Late-Filed Return

§179 election generally must be made on a timely-filed return (including extensions). Late filing may forfeit §179 unless Rev. Proc. 2008-54 reasonable cause relief is available. Verify timeliness of original filing before relying on §179.

Primary authority: IRC §179 (election to expense certain depreciable business assets), §179(b) (limitations), §179(b)(1) (dollar limitation - $2.5M baseline post-OBBBA, $2,560,000 for 2026), §179(b)(2) (reduction in limitation - $4M baseline, $4,090,000 for 2026), §179(b)(3) (limitation based on income from trade or business), §179(b)(3)(B) (carryover of disallowed deduction), §179(b)(4) (limitation on listed property), §179(b)(5) (limitation on SUVs - $32,000 for 2026), §179(b)(5)(B) (exception for heavy trucks/vans with cargo bed), §179(c) (election), §179(c)(2) (revocation of election - without IRS consent for tax years beginning after 2002), §179(d) (definitions and special rules), §179(d)(1) (§179 property definition), §179(d)(2) (excluded property - related party / inherited / gift), §179(d)(8) (partnership and S-corp), §179(d)(10) (recapture for business use drop below 50%), §179(f) (qualified real property - QIP, roofs, HVAC, fire/alarm/security). §168 (MACRS), §168(e)(6) (QIP definition), §168(k) (bonus depreciation - 100% permanent under OBBBA for property after 1/19/2025), §168(g) (ADS). §280F (luxury auto / listed property). §50(b)(2) (lodging exclusion). §162 (trade or business). §163(j) (business interest limit - §179 treated as amortization for ATI; EBITDA ATI permanent under OBBBA). One Big Beautiful Bill Act, P.L. 119-21, §70302 (§179 doubled baseline to $2.5M / $4M, permanent), effective property placed in service in tax years beginning after December 31, 2024. Treasury Regulations §1.179-1 through §1.179-5. Rev. Proc. 2008-54 (late election). IRS Form 4562 (Depreciation and Amortization) and Instructions, Form 4797 (Sales of Business Property - §179 recapture).