Cost segregation is a tax strategy that accelerates depreciation on your short-term rental (STR) by reclassifying components of the property—wiring, plumbing, flooring, cabinetry, landscaping—from the standard 27.5-year residential depreciation schedule to 5-, 7-, or 15-year schedules. For a typical Seattle STR purchased at $700,000–$900,000, a cost segregation study can generate $20,000–$60,000 in additional first-year deductions that would otherwise be spread across three decades.
Key takeaways
- Standard residential depreciation spreads your deduction over 27.5 years. Cost segregation reclassifies components to 5–15 year schedules, front-loading those deductions.
- Bonus depreciation was permanently reinstated at 100% by the One Big Beautiful Bill Act (OBBBA) for qualified property acquired and placed in service after January 19, 2025. There is no longer a phase-out schedule. This means the entire reclassified component value can be deducted in year one.
- To use the deductions against ordinary income (W-2 wages, for example), you must meet the IRS "material participation" or "real estate professional" test.
- A cost segregation study typically costs $3,000–$8,000 and should be commissioned by a licensed engineer, not a general CPA.
- The strategy is most impactful for properties purchased or substantially renovated in the last 5 years.
What standard depreciation actually gives you
When you buy a residential rental property, the IRS lets you deduct its cost basis (purchase price minus land value) over 27.5 years in equal annual installments. For a Seattle STR with a $750,000 purchase price and $100,000 allocated to land, the depreciable basis is $650,000. Standard annual depreciation: $650,000 ÷ 27.5 = $23,636 per year.
That's not nothing—but it's spread thin.
Cost segregation studies, conducted by licensed engineers and CPAs, identify building components that qualify for shorter recovery periods under IRS asset classification rules. Instead of waiting 27.5 years to fully depreciate the kitchen cabinets, the electrical system, and the decorative landscaping, you depreciate them in 5, 7, or 15 years. The deduction amount is the same over a property's lifetime; the timing shifts dramatically in your favor.
What gets reclassified—and to what schedule
Cost segregation engineers conduct a detailed physical inspection of the property and assign each component a cost and recovery period based on IRS guidelines. Common reclassifications for a Seattle STR:
5-year property (most impactful):
- Carpeting and specialty flooring
- Kitchen appliances (if not permanently attached)
- Decorative light fixtures
- Window treatments
- Certain plumbing fixtures
7-year property:
- Office furniture and equipment
- Some cabinetry and millwork
15-year land improvements:
- Landscaping and irrigation systems
- Parking areas and driveways
- Fencing and outdoor lighting
- Sidewalks and retaining walls
For a well-furnished Seattle STR, 15–25% of the total purchase price can typically be reclassified to shorter lives.
Bonus depreciation: the permanent reinstatement
Under the One Big Beautiful Bill Act (OBBBA), 100% bonus depreciation has been permanently reinstated for qualified property acquired and placed in service after January 19, 2025. There is no longer a phase-down schedule or expiration date under current law. This is a significant change from the previous rules that had been reducing the bonus depreciation rate annually (80% in 2023, 60% in 2024, 40% in 2025 under the old schedule).
What this means in practice: if a cost segregation study identifies $150,000 of components reclassifiable to 5-, 7-, or 15-year schedules, and the property was acquired or placed in service after January 19, 2025, you can deduct the full $150,000 in the year of the study—not spread over the shorter depreciation schedule.
For properties acquired before January 19, 2025, the pre-OBBBA phase-down rates apply based on when the property was placed in service. If your property falls in that window, confirm the applicable rate with your CPA.
The material participation requirement
Here is the critical constraint: depreciation deductions generated by rental real estate are classified as "passive losses" by the IRS. Passive losses can only offset passive income—not your W-2 wages, self-employment income, or interest and dividends—unless you meet one of two exceptions:
Exception 1: $25,000 passive activity allowance If your modified adjusted gross income (MAGI) is below $100,000, you can deduct up to $25,000 of rental losses against ordinary income. This allowance phases out completely above $150,000 MAGI. For most high-income Seattle property owners, this exception is unavailable.
Exception 2: Short-term rental material participation Short-term rentals (average guest stay of 7 days or fewer) are not subject to the passive activity rules at all—if you materially participate. Material participation means one of seven tests is met; the most practical for STR owners is spending more than 100 hours on the activity during the year and more hours than any other individual.
If you materially participate in your Seattle STR and the average stay is 7 days or fewer, depreciation losses—including accelerated losses from cost segregation—can directly offset your W-2 or other ordinary income. We cover material participation in detail in Why many STR landlords lose tax benefits.
Exception 3: Real estate professional status If you (or your spouse) qualify as a real estate professional under IRS rules—meaning you spend more than 750 hours per year in real estate activities and that represents more than half your working time—all rental losses are non-passive and deductible against ordinary income without restriction.
Is a cost segregation study worth it for your property?
The quick test: if the additional first-year deduction multiplied by your marginal tax rate exceeds the study cost, the study pays for itself immediately.
Example: A $900,000 Seattle STR acquired after January 19, 2025, with 20% of purchase price reclassifiable = $180,000 in accelerated components. With 100% bonus depreciation under the OBBBA, that's a full $180,000 immediate deduction in year one. At a 37% federal marginal rate, tax savings: $66,600. Study cost: $5,000. Net benefit in year one: $61,600.
The math generally works for properties valued at $500,000 or more. Below that threshold, study costs begin to approach or exceed the near-term tax benefit.
Additional situations where cost seg makes strong sense:
- You recently renovated a property significantly (a look-back study can capture reclassification retroactively)
- You have passive income from other sources that needs offsetting
- You're planning to hold the property long-term and want to time deductions to high-income years
One risk to understand: depreciation recapture
When you eventually sell the property, the IRS recaptures accelerated depreciation at a 25% rate (Section 1250 recapture) rather than the long-term capital gains rate. This is not a reason to avoid cost segregation—the time value of money still strongly favors acceleration—but it means your exit strategy matters. A 1031 exchange on sale defers both the capital gain and the depreciation recapture, which is why many investors combine cost segregation with a long-term exchange strategy.
What URPM can help with
URPM works with Seattle STR investors on the full ownership lifecycle—from acquisition analysis to tax-efficient exit. We can introduce you to licensed cost segregation engineers and CPAs who specialize in Washington state STR real estate, ensure your property's rental records support material participation documentation, and evaluate whether your property's income profile makes the study worthwhile before you commission it.
Frequently asked questions
Can I do a cost segregation study on a property I bought years ago? Yes. A "look-back" study lets you claim the missed depreciation in the current tax year via a Form 3115 (Change in Accounting Method), without amending prior returns. This is one of the most underused tax tools for STR owners who bought before learning about cost seg.
Does cost segregation work for condos? Yes, though the reclassifiable percentage is typically lower than for single-family homes because condos contain fewer land improvements and exterior components. Interior personal property and certain building systems still qualify.
What if I sell before the depreciation schedule ends? You'll owe depreciation recapture tax (25% on Section 1250 recapture) on the accelerated deductions you've taken. Unless you execute a 1031 exchange, plan for this tax event in your exit modeling.
Related reading: How to offset W-2 income with short-term rentals and 1031 exchange and short-term rentals: what Seattle investors need to know.