AMT and Accelerated Depreciation: When Bonus Depreciation Creates a Preference Item

The alternative minimum tax (AMT) system treats depreciation differently than regular tax law; accelerated depreciation—especially bonus depreciation on real assets—creates a “preference item” that adds back the excess deduction, potentially triggering AMT for high-income taxpayers and real-estate or equipment investors.

The AMT Depreciation Adjustment Explained

The AMT system requires taxpayers to recalculate taxable income using a separate set of rules. For depreciation, the key difference is that the AMT uses the Alternative Depreciation System (ADS), which is slower than the Modified Accelerated Cost Recovery System (MACRS) allowed under regular tax.

For example, a commercial building purchased for $1,000,000 under regular tax uses straight-line depreciation over 39 years (roughly $25,641 per year). This is already straight-line but is the baseline. For AMT, the same building must also use a 40-year ADS life, producing roughly $25,000 per year. The difference is small here, but when bonus depreciation is involved, the gap widens dramatically.

A piece of equipment (5-year property under MACRS) bought in a year when 100% bonus depreciation is available can be fully deducted in year 1 under regular tax. Under AMT, the same equipment must be depreciated over its ADS life (often 6 or 10 years, depending on the asset type), producing roughly 10% to 20% of the deduction in year 1 and the remainder spread over the remaining ADS life.

How the Preference Item Triggers AMT

On Form 6251 (Alternative Minimum Tax—Individuals), the taxpayer computes AMT taxable income by:

1. Starting with regular taxable income.
2. Adding back (or subtracting) adjustments, including the excess depreciation.
3. Computing taxable income under AMT rules.
4. Applying the AMT tax rate (26% or 28%, vs. regular tax brackets).

The depreciation preference item is the excess of regular-tax depreciation over AMT depreciation for the year. If a taxpayer claims $100,000 in bonus depreciation in year 1 but can only deduct $10,000 under ADS, the preference item is $90,000—added back into AMT income. That $90,000 triggers AMT at 26% (or higher if other preferences apply), potentially creating a tax bill even though the regular tax liability is low or zero.

Over the multi-year recovery period, the preference reverses: in years 2–6, the taxpayer deducts less under regular tax than under ADS (because the full bonus deduction was taken in year 1), creating negative adjustments on Form 6251 that reduce AMT taxable income.

Common Scenarios for Real-Estate and Equipment Investors

Real-estate investors have historically seen smaller AMT exposure from depreciation alone, since residential and commercial buildings use similar straight-line recovery lives under both systems. However, cost-of-equity financing of acquisitions combined with large depreciation recapture can trigger AMT.

Equipment investors and lessors are most exposed. A company purchasing heavy machinery, vehicles, or IT equipment in a year with bonus depreciation can generate enormous regular-tax deductions in year 1. If the taxpayer’s regular tax is already low (due to other losses or deductions), that bonus depreciation adds only a small tax benefit. The AMT, by contrast, treats the bonus as a preference adjustment, potentially creating surprise AMT liability.

Asset-backed businesses—trucking fleets, equipment rental companies, restaurant chains with owned locations—often have high depreciation relative to cash income. They can inadvertently trigger AMT in high-revenue years if they are not monitoring preferences.

Calculating and Avoiding AMT Exposure

Taxpayers can plan around AMT exposure by:

• Electing out of bonus depreciation: Under IRC Section 168(k), a taxpayer can decline bonus depreciation and use regular MACRS schedules instead. This eliminates the preference item but forgoes the upfront deduction.
• Spreading acquisitions: Instead of buying all assets in one year, spreading purchases across years can smooth depreciation deductions and reduce the concentration of AMT triggers.
• Timing income recognition: In years where income is expected to be high, deferring additional asset purchases can limit the risk that bonus depreciation creates AMT liability.
• Monitoring Form 6251 projections: High-income taxpayers should run AMT calculations during the year to avoid surprises.

The AMT Credit and Carryforward

A key relief provision: if a taxpayer pays AMT due to preferences, they may earn an AMT credit equal to the excess AMT paid. This credit can offset regular tax liability in future years, converting the AMT from a permanent tax to a deferral. The credit is non-refundable (absent limited exceptions), so it only helps if the taxpayer has regular tax liability in later years.

A real-estate investor who pays $50,000 in AMT due to bonus depreciation in year 1 can claim $50,000 of AMT credit in years 2 and beyond, reducing regular tax dollar-for-dollar. If the investor sells the property and recognizes ordinary income (or has other high-income years), the AMT credit can be fully absorbed.

Interaction With Depreciation Recapture

When an asset is sold, depreciation recapture requires the taxpayer to recapture the excess of accelerated (or bonus) depreciation claimed. Under regular tax, the recapture is ordinary income taxed at ordinary rates. Under AMT, the recapture still applies, but the taxpayer’s AMT basis (and thus the recapture amount) reflects the slower ADS depreciation. This creates a further adjustment on the AMT return at sale.

The interplay is complex: a taxpayer who claimed bonus depreciation (creating an AMT preference in year 1), paid AMT, used the credit in subsequent years, and then sells the property will need to carefully reconcile regular tax and AMT depreciation bases to avoid double-counting recapture.

See also