Business Jet Tax Depreciation: Section 168, Bonus Depreciation, and What Changed in 2026

The Depreciation Landscape in 2026

The Tax Cuts and Jobs Act of 2017 (TCJA) introduced 100% bonus depreciation for qualified property, including business aircraft, placed in service between September 27, 2017, and December 31, 2022. This provision allowed a buyer to deduct the entire acquisition cost of a business jet in the year of purchase, creating a tax benefit that materially influenced purchasing decisions across business aviation. A company acquiring a $25 million Gulfstream G550 in 2021 could deduct the full $25 million from taxable income in the year of acquisition.

That era is ending. The TCJA included a phase-down schedule: 80% bonus depreciation in 2023, 60% in 2024 and 2025 (extended), and 40% in 2026. Without congressional action, bonus depreciation drops to 0% on January 1, 2027. Buyers in 2026 face a 60% first-year bonus deduction with the remaining 40% spread across the standard MACRS (Modified Accelerated Cost Recovery System) 5-year schedule. The urgency to transact before year-end 2026 is palpable: aircraft sales advisors report a 25-30% increase in Q3-Q4 acquisition activity as buyers attempt to capture the remaining bonus depreciation before it phases out entirely.

Section 168 MACRS: The Standard Depreciation Framework

Under Section 168, business aircraft are classified as 5-year MACRS property. Without bonus depreciation, the aircraft's cost is recovered over 6 calendar years using the double-declining-balance method with a half-year convention. The first-year deduction is 20% of cost. With 2026's 60% bonus depreciation, the first-year deduction jumps to approximately 68% of cost (60% bonus plus 20% MACRS on the remaining 40%). For a $25 million aircraft, that is $17 million deducted in Year 1.

The 'placed in service' date is the critical threshold for bonus depreciation, not the purchase date or delivery date. An aircraft is placed in service when it is ready and available for its intended use. For new aircraft, this typically means the date the FAA issues the airworthiness certificate and the buyer takes physical delivery. For pre-owned aircraft, it is the date the buyer completes acquisition and the aircraft is operational for business use. December closings require careful coordination between the closing attorney, FAA registry, and the buyer's tax counsel.

Business Use Requirements: The 50% Threshold

Section 168 and bonus depreciation apply only if the aircraft is used more than 50% for qualified business purposes in the year it is placed in service. If business use falls below 50% in any subsequent year, the taxpayer must recapture previously claimed depreciation exceeding what would have been allowed under the straight-line method. This recapture provision creates a compliance obligation that extends for the entire depreciation period.

• Qualified business use: Flights directly related to the taxpayer's trade or business, including client meetings, site visits, and business development
• Entertainment disallowance: Post-2018 tax reform eliminated deductions for entertainment use. Flights to sporting events, concerts, or purely social gatherings do not qualify as business use
• Commuting exclusion: Regular commuting between home and office does not constitute business use under Section 274
• Mixed-use flights: When a flight combines business and personal purposes, only the business portion qualifies. The IRS scrutinizes 'primary purpose' determinations
• Documentation: The IRS requires contemporaneous records of each flight: date, origin, destination, business purpose, passengers, and flight hours. Aircraft logbooks must support the claimed business use percentage

The IRS audits aircraft depreciation claims at a higher rate than most business asset categories. The combination of high dollar amounts, mixed-use potential, and lifestyle association makes business aircraft a persistent audit target. Tax courts have disallowed depreciation deductions where owners could not produce contemporaneous flight logs demonstrating the 50% business use threshold. Every flight must be documented with business purpose at the time it occurs, not reconstructed during audit preparation.

Post-Bonus Strategies: 1031 Exchanges and Cost Segregation

As bonus depreciation phases to zero, alternative tax strategies gain importance. Like-kind exchanges under Section 1031 allow aircraft owners to defer capital gains taxes when selling one aircraft and acquiring a replacement. The exchange must involve property of 'like kind' (any business aircraft qualifies as like-kind to any other business aircraft), and the transaction must follow strict IRS timelines: 45 days to identify replacement property, 180 days to close the acquisition.

A Section 1031 exchange does not eliminate the tax liability; it defers the gain into the replacement aircraft's reduced basis. An owner who purchased a G550 for $20 million, depreciated it to $5 million, and sold it for $18 million would face a $13 million taxable gain. Through a 1031 exchange into a $25 million G650, the $13 million gain is deferred, and the new aircraft's depreciable basis is reduced to $12 million ($25M - $13M deferred gain). The strategy preserves capital for the acquisition and delays the tax event.

Qualified Opportunity Zone investments have attracted some aircraft owners as a partial alternative to 1031 exchanges for gain deferral. However, QOZ investments require the gain to be reinvested in designated opportunity zones within 180 days, and the investment must be maintained for at least 10 years to achieve full tax benefits. QOZ and 1031 strategies serve different purposes: 1031 exchanges roll gains into replacement aircraft, while QOZ investments redirect gains into real estate or business investments in designated zones.

What to Model Before Signing the Purchase Agreement

The decision to acquire in 2026 versus 2027 is ultimately a time-value-of-money calculation. At 60% bonus depreciation, a buyer in the 37% federal bracket recovers 22.2% of the acquisition cost in Year 1 federal tax savings. On a $20 million aircraft, that is $4.44 million. At 0% bonus depreciation in 2027, the Year 1 recovery drops to 7.4% ($1.48 million). The $2.96 million difference in first-year tax benefit, discounted at the buyer's cost of capital, represents the economic value of transacting before December 31, 2026.