Section 179 vs Bonus Depreciation in 2026: When to Use Each (and How to Stack Both)

Section 179 expensing in 2026 under OBBBA

Section 179 under IRC Section 179(b) allows a current-year deduction for the cost of qualifying property in lieu of depreciation. OBBBA raised the dollar limitation to $2,500,000 and the phaseout threshold to $4,000,000 of qualifying property placed in service in the year. Above the phaseout threshold, the $2.5M cap reduces dollar-for-dollar with the excess, reaching zero at $6.5M of qualifying property.

Qualifying property under Section 179 includes tangible personal property, off-the-shelf software, qualified improvement property, and certain real property improvements added by the TCJA (roofs, HVAC, fire protection, alarm systems, security systems) on nonresidential real property. Residential rental property does not qualify for Section 179 because it is not used in a trade or business under the active-conduct standard.

The election is annual and made on a property-by-property basis. The taxpayer can elect Section 179 on some assets and use bonus depreciation on others in the same year. The election is made on Form 4562 attached to the return for the year of placed-in-service.

Bonus depreciation under amended Section 168(k)

Section 168(k) bonus depreciation under OBBBA is 100% for property acquired and placed in service after January 19, 2025. Property under binding contract on or before January 19, 2025 follows the legacy phase-down: 40% in 2025, 20% in 2026, 0% in 2027 and after. The Bonus Depreciation Timing Window framework on this site explains the cliff in detail.

Bonus depreciation applies automatically to all bonus-eligible property unless the taxpayer makes an opt-out election. The election applies on a class-by-class basis under Section 168(k)(7). Most real estate investors do not opt out because the 100% deduction is the goal of the cost segregation strategy.

Bonus depreciation has no income limitation. It can create a net operating loss that carries forward indefinitely under post-TCJA rules. This is the single largest practical difference from Section 179, which is income-limited.

The income limitation gap

Section 179 is limited under Section 179(b)(3) to the taxpayer's aggregate net income from any trade or business actively conducted by the taxpayer. Rental real estate is generally not an active trade or business unless the activity meets the heightened threshold established in case law (Hilton v. Commissioner, Murtaugh v. Commissioner, Curphey v. Commissioner). For most rental investors, the trade-or-business income limitation reduces or eliminates the Section 179 deduction in the year of election.

Bonus depreciation has no equivalent limitation. A bonus depreciation deduction can produce a net rental loss, which is then subject to passive activity loss rules under Section 469 but is not itself capped. If the taxpayer is REPS-qualified or qualifies under the STR loophole, the rental loss is nonpassive and offsets W-2 and other active income directly.

Practically, this means most real estate investors use bonus depreciation as the primary deceleration tool and reserve Section 179 for genuinely active trade-or-business contexts (an operating restaurant, a self-managed self-storage business, an active short-term-rental hotel operation where substantial services are provided).

When to elect Section 179 over bonus

Several scenarios favor Section 179. First, state decoupling. Many states fully decouple from Section 168(k) bonus depreciation but accept Section 179 expensing in some form, often with a reduced state cap. California, for example, decouples from bonus but allows a $25K state Section 179 deduction. Hawaii, New Jersey, and others have similar structures. For investors in decoupling states, Section 179 produces some state benefit where bonus produces none.

Second, property that needs to be quickly converted or traded. Section 179 has different recapture rules from bonus depreciation that simplify some downstream transactions. The exact mechanics depend on the property type and structure.

Third, properties where the income limitation is not a constraint. An active trade-or-business owner with substantial trade-or-business income from a different activity can use Section 179 against that income. The cross-activity aggregation works for taxpayers whose entire income is from active trades or businesses.

When to stack both in the same year

Section 179 and bonus depreciation can both apply in the same year on different assets, or on the same asset in sequence. The election is property-by-property. The taxpayer can carve out a Section 179 election on assets where state benefit matters and let bonus depreciation apply to the rest.

The order of application matters. Section 179 is taken first, reducing the property's basis. Bonus depreciation then applies to the remaining basis at the 100% rate. Regular MACRS depreciation applies to what remains after Section 179 and bonus. For 100% bonus on personal property, the regular MACRS layer is zero after bonus, so the order is academic. For phase-down-era property, the order can produce slightly different first-year numbers.

State conformity matters more than the federal choice

The federal Section 179 versus bonus choice is mostly academic for taxpayers in rolling-conformity states. Both produce the same federal deduction. The state-level treatment is where the choice matters.

Roughly a dozen states fully decouple from federal Section 168(k) and require a complete addback. Some of those states still permit a state-level Section 179 deduction at a capped amount. For investors in those states, Section 179 captures state-level benefit on a portion of the reclassified basis that bonus would lose.

Other states have rolling conformity (Colorado, Alabama, Missouri, North Dakota, Oklahoma, Kansas, Tennessee, and others). In these states, federal bonus depreciation is matched at the state level. Section 179 produces no additional state benefit over bonus.

See the state pages for state-by-state OBBBA conformity treatment and the relevant Section 179 cap where applicable.

Cost segregation amplifies both

A cost segregation study reclassifies 20-40% of basis into 5-, 7-, and 15-year property. The reclassified portion is fully eligible for both Section 179 (subject to the income limitation and dollar caps) and bonus depreciation. The classification work is the same. Only the election differs.

For commercial property where some of the reclassified components fit Section 179's expanded list (HVAC, roof improvements, fire protection, alarms), the cost seg report often includes a Section 179 recommendation alongside the bonus depreciation recommendation. The taxpayer's CPA makes the final election based on the year-specific income, state, and entity context.