Cost Segregation on a Rental: The Year-One Tax Lift That Pays for the Study

Standard residential rental depreciation is straight-line over 27.5 years. A cost segregation study reclassifies portions of the property into shorter recovery periods — 5-year, 7-year, and 15-year property — which depreciate faster and (in some years) qualify for bonus depreciation on top.

On a $400k rental, a typical cost-seg study identifies $60–110k of components that should not have been on the 27.5-year schedule. Reclassified and bonus-depreciated, that can produce $25–50k of additional first-year deduction. On a $7,500 study fee, that is a payback measured in months.

General education, not tax advice. Cost seg eligibility, bonus percentages, and the recapture math at exit are all moving targets — current law in 2026 is not the same as 2024. A real estate CPA + a qualified cost-seg engineer is required for any actual application.

What cost segregation actually does

A cost segregation study is an engineering-based analysis that breaks a building into its components and assigns each component to its correct IRS recovery period:

• 5-year property: carpeting, appliances, decorative lighting, decorative millwork, certain landscaping. ~5–8% of building basis on typical SFR.
• 7-year property: some specialty equipment.
• 15-year property: land improvements — driveways, sidewalks, fencing, exterior landscaping, parking areas, exterior lighting. ~8–15% of basis on typical SFR.
• 27.5-year property: structural building components — walls, roof, foundation, framing, plumbing, HVAC. The default rental class.

Without a cost seg study, the entire building basis is depreciated over 27.5 years by default. The study moves the carve-outs to their correct shorter classes, where they produce larger annual deductions.

The bonus depreciation layer

Beyond the recovery-period reclassification, property with a recovery period of 20 years or less is eligible for bonus depreciation — an immediate first-year write-off of a percentage of the asset's cost.

• 2017–2022: 100% bonus on qualifying property (the TCJA peak)
• 2023: 80%
• 2024: 60%
• 2025: 40%
• 2026: 20%
• 2027 and beyond (under current law): 0% (sunsets, unless Congress extends)

Bonus depreciation rates have been a moving target — extensions and reinstatements have happened repeatedly. Check current law with a CPA before underwriting any specific bonus percentage into a deal.

Worked example — $400k SFR rental, 2026 acquisition

Operator buys a $400,000 rental. Land allocation: $80,000. Depreciable basis: $320,000.

Without cost seg:

• Year-1 depreciation: $320,000 ÷ 27.5 ≈ $11,636

With cost seg study identifying 8% as 5-year property ($25,600), 10% as 15-year property ($32,000), remaining 82% as 27.5-year ($262,400):

• 5-year property regular depreciation: $25,600 × first-year double-declining = $5,120
• 5-year bonus depreciation (20% of remaining basis after regular): ($25,600 − $5,120) × 20% = $4,096
• 15-year property regular depreciation: $32,000 × first-year MACRS = $1,600
• 15-year bonus depreciation: ($32,000 − $1,600) × 20% = $6,080
• 27.5-year (unchanged): $262,400 ÷ 27.5 = $9,542
• Total year-1 with cost seg: ~$26,438

That is roughly $15,000 more first-year deduction than the straight-line case. For a high-income operator in the 32% federal + 6% state bracket, that converts to about $5,700 of cash tax savings in year one. On a $7,500 cost seg study, that is roughly a 15-month payback from the year-one tax lift alone — not counting the compounded effect of larger deductions in years 2–5.

When cost seg pencils

• Property basis > $300k. Studies on smaller properties have a hard time generating enough reclassification to cover the $5–10k study fee.
• Operator has passive activity income to offset. Cost seg generates passive losses; they need passive income or material participation (REPS) to be useful in the current year.
• Hold period > 5 years projected. Recapture is harsher on a short hold; the tax-deferral value compresses.
• Operator is in a high tax bracket. The marginal tax rate determines the actual cash value of an extra dollar of deduction.

The recapture trap

Bonus depreciation feels like free money but it is not — it is acceleration, not creation. The accelerated depreciation accumulates faster, which means accumulated depreciation at any given sale year is larger, which means recapture at sale is larger.

Worse, depreciation taken on 5-year and 15-year property is recaptured as ordinary income under Section 1245, not at the 25% rate that applies to Section 1250 recapture on 27.5-year building property. For a high-bracket operator that is a 37% federal rate on the Section 1245 portion at sale.

The fix: model recapture into the exit-year cash flow when evaluating cost seg. The NPV calculation answers the question, not the gross first-year deduction. See depreciation recapture on a BRRRR exit.

When NOT to cost seg

• Short flip-style hold. If the property is being held under 3 years, the deferral value is too small to cover the study fee and recapture.
• No income to offset. Passive losses without passive income or REPS just stack as suspended losses — useful eventually, but no current-year cash value.
• Low tax bracket. If marginal rate is under 22%, the cash value per dollar of deduction is small.
• 1031 planned at exit. If the operator will 1031 the property forward, recapture defers anyway and the study is less critical.

Related reading

• Depreciation recapture on a BRRRR exit
• 1031 exchange for fix and flip investors
• Dealer status vs investor
• BRRRR definition