Section 168 and Section 179 are two different routes for deducting the cost of business property. Section 168 houses both the default MACRS depreciation schedule, which spreads an asset’s cost across a set recovery period, and bonus depreciation, which after the One, Big, Beautiful Bill is back to a permanent 100 percent first-year write-off with no dollar cap. Section 179 lets you elect immediate expensing on qualifying property up to $2,560,000 for tax years beginning in 2026, but only to the extent of your active business income. The choice between Section 168 vs 179 depreciation comes down to how much you’re buying, what type of property it is, and whether you want the deduction to be able to create a loss.
The Core Difference
Section 168 is automatic and mechanical. MACRS is the default depreciation method for tangible business property, and bonus depreciation under Section 168(k) applies to qualifying assets by default unless you elect out. Neither has a dollar cap. Bonus depreciation, in particular, can drive taxable income below zero and generate a net operating loss.1Office of the Law Revision Counsel. 26 U.S. Code 168 – Accelerated Cost Recovery System
Section 179 is elective and selective. You choose which assets to expense, and how much to expense on each one, by filing Form 4562. The deduction is capped at $2,560,000 for 2026, phases down dollar-for-dollar once total qualifying purchases exceed $4,090,000, and disappears entirely at $6,650,000.2Internal Revenue Service. Publication 946 – How To Depreciate Property And Section 179 cannot exceed your total taxable income from active trades or businesses, so it can never create or deepen a loss.3Office of the Law Revision Counsel. 26 U.S. Code 179 – Election to Expense Certain Depreciable Business Assets
What Section 168 Covers
Section 168 does two jobs. The first is MACRS, the Modified Accelerated Cost Recovery System, which is what applies to any depreciable asset when neither Section 179 nor bonus depreciation is in play. Recovery periods run from three years for over-the-road tractor units up to 39 years for nonresidential commercial buildings, with automobiles and computers falling in the 5-year class and office furniture in the 7-year class. Personal property in the 3-, 5-, and 7-year classes uses the 200 percent declining balance method, which front-loads deductions into the early years; real property uses straight-line.4Internal Revenue Service. Publication 946 – How To Depreciate Property
The second job is bonus depreciation under Section 168(k). The Tax Cuts and Jobs Act put 100 percent bonus depreciation on a phase-down schedule that would have dropped it to 20 percent in 2026 and eliminated it in 2027. The One, Big, Beautiful Bill restored a permanent 100 percent deduction for qualified property acquired after January 19, 2025.5Internal Revenue Service. Treasury, IRS Issue Guidance on the Additional First Year Depreciation Deduction Amended as Part of the One, Big, Beautiful Bill The acquisition date matters: property acquired before January 20, 2025, stays on the original phase-down schedule.
Bonus depreciation covers tangible personal property with a MACRS recovery period of 20 years or less, and it works for both new and used assets, provided you had no prior ownership interest, didn’t acquire it from a related party, and didn’t use it before buying it.6eCFR. 26 CFR 1.168(k)-1 – Additional First Year Depreciation Deduction Nonresidential real property, residential rental property, property required to use the Alternative Depreciation System, and related-party acquisitions do not qualify.
For the first tax year ending after January 19, 2025, you can elect to take 40 percent instead of the full 100 percent (60 percent for long-production-period property and certain aircraft), which is useful if you’d rather spread deductions across future years.5Internal Revenue Service. Treasury, IRS Issue Guidance on the Additional First Year Depreciation Deduction Amended as Part of the One, Big, Beautiful Bill
What Section 179 Does Differently
Section 179 covers tangible personal property used in the active conduct of a trade or business: machinery, equipment, off-the-shelf computer software. It also reaches property that bonus depreciation typically won’t touch, including qualified real property such as interior improvements to nonresidential buildings, roofs, HVAC systems, fire protection and alarm systems, and security systems.3Office of the Law Revision Counsel. 26 U.S. Code 179 – Election to Expense Certain Depreciable Business Assets The asset must be purchased, not gifted or inherited, and used in a business you actively operate.
The taxable income cap is the biggest structural difference from bonus depreciation. If you elect $1,000,000 of Section 179 but your business only shows $800,000 of income, your current-year deduction is capped at $800,000. The disallowed $200,000 carries forward indefinitely and can be deducted in any future year with enough business income.3Office of the Law Revision Counsel. 26 U.S. Code 179 – Election to Expense Certain Depreciable Business Assets Nothing is lost, but nothing creates a loss either.
A Section 179 election can be made, changed, or revoked on an amended return within the IRS’s amendment window for that tax year. No IRS permission is needed to revoke, but once revoked, the revocation is irrevocable for that year.7Internal Revenue Service. Instructions for Form 4562
The Order the Deductions Apply
When both provisions could apply to the same asset, the sequence is mandatory. The Form 4562 instructions put it plainly: “The special depreciation allowance is an additional deduction you can take after any section 179 expense deduction and before you figure regular depreciation under MACRS.”7Internal Revenue Service. Instructions for Form 4562
- Section 179 comes off the top and reduces the cost basis.
- Bonus depreciation applies to the remaining basis.
- Regular MACRS depreciation runs on whatever basis is left.
The Treasury regulations illustrate with a $126,000 asset: a $100,000 Section 179 deduction reduces basis to $26,000, 50 percent bonus depreciation (using the older percentage in the example) deducts $13,000, and the remaining $13,000 runs through MACRS.6eCFR. 26 CFR 1.168(k)-1 – Additional First Year Depreciation Deduction With 100 percent bonus depreciation back in force for 2026, taking full bonus on the entire cost simply zeros out the basis in step two, so the ordering rarely changes the outcome unless you’re electing out of bonus for a class of property or working with an asset that qualifies for one provision but not the other.
When Section 179 Beats Bonus, and When Bonus Wins
With permanent 100 percent bonus depreciation, it’s tempting to treat Section 179 as obsolete. It isn’t, because the two provisions solve different problems.
Use Section 179 when you want control. Bonus depreciation is all-or-nothing for each class of property: you either take 100 percent on every qualifying asset in the class or elect out of the entire class. Section 179 lets you pick individual assets and dial the deduction to whatever amount makes sense. A business with $500,000 of taxable income can elect exactly $500,000 of Section 179, keep the rest on regular MACRS, and end the year at zero taxable income without generating an NOL.
Use Section 179 for qualified real property. Interior improvements, roofs, HVAC, fire protection, and security systems in nonresidential buildings are Section 179-eligible even when they don’t meet bonus depreciation’s acquisition-date rules.3Office of the Law Revision Counsel. 26 U.S. Code 179 – Election to Expense Certain Depreciable Business Assets
Use Section 179 when you want to avoid a loss. The taxable income cap acts as an automatic guardrail against creating an NOL that might face carryforward limitations later. Bonus depreciation has no such guardrail.
Use bonus depreciation when the purchase is large. If you spend past the $2,560,000 Section 179 ceiling, or hit the $4,090,000 phase-out threshold, bonus depreciation still fully deducts the excess in year one. It’s also the right tool when you want a loss, whether to offset other income streams or to carry forward against expected future profits.
Use bonus depreciation for used equipment purchases that meet its acquisition rules, since it doesn’t require any active-business-income calculation.
Vehicles Change the Math
Depreciation on business vehicles runs into Section 280F’s luxury auto caps, and those caps override both Section 179 and bonus depreciation for passenger automobiles. For a passenger vehicle placed in service in 2026, the maximum first-year deduction is $20,300 with bonus depreciation or $12,300 without, followed by $19,800 in year two, $11,900 in year three, and $7,160 per year after that.8Internal Revenue Service. Revenue Procedure 2026-15 A $60,000 sedan used entirely for business takes about six years to fully depreciate no matter which provision you use.
Vehicles with a gross vehicle weight rating over 6,000 pounds escape the passenger-auto caps. SUVs in the 6,000-to-14,000-pound range face their own Section 179 cap of roughly $32,000 for 2026 rather than the full $2,560,000, but they still qualify for unrestricted 100 percent bonus depreciation. Trucks and vans built for cargo, and vehicles over 14,000 pounds, don’t face the SUV-specific cap at all. That’s how a $75,000 heavy truck used entirely for business can be fully deducted in year one.
All vehicles and other listed property must be used more than 50 percent for business to qualify for Section 179 or bonus depreciation. Business use of 70 percent means you deduct 70 percent of the otherwise allowable amount. If business use drops to 50 percent or less in a later year, you have to recapture prior excess depreciation and switch to straight-line going forward.9eCFR. 26 CFR 1.280F-6 – Special Rules and Definitions
State Conformity Isn’t Automatic
Federal and state depreciation rules diverge often enough to matter. Roughly 15 states fully conform to federal bonus depreciation; others allow a fraction or decouple entirely. About 12 states set their own Section 179 caps, ranging from $25,000 to $500,000 rather than following the federal $2,560,000.
The OBBB’s restoration of permanent 100 percent bonus depreciation does not flow automatically to every state return. Some states conform to the Internal Revenue Code as of a fixed date and won’t pick up the OBBB changes until the legislature updates the conformity date. Others decouple from bonus depreciation as a standing rule. Check your state’s current position before assuming the federal deduction reduces state taxable income by the same amount.