The STR loophole is the mechanism that makes rental losses non-passive. Cost segregation is the engine that creates those losses in the first place. Understanding how they work together is essential for maximizing your tax savings.
Without cost segregation, a rental property generates a modest annual depreciation deduction. With it — and with 100% bonus depreciation restored under the OBBBA — you can deduct a significant portion of your property's value in year one.
- Residential rental property normally depreciates over 27.5 years. Cost segregation accelerates this by reclassifying components into 5-, 7-, and 15-year categories.
- With 100% bonus depreciation restored permanently under the OBBBA, all reclassified assets can be fully deducted in year one.
- A typical study on a $400,000–$500,000 STR generates $60,000–$120,000 in year-one deductions.
- Without the STR loophole, these losses would be passive and suspended. With it, they offset your W-2 income.
What Is Cost Segregation?
Cost segregation is an IRS-approved engineering analysis that breaks a property into its component parts and assigns each component to the appropriate depreciation category.
Under normal tax rules, everything in a residential rental property depreciates over 27.5 years. But the IRS recognizes that not every component has a 27.5-year useful life. Appliances wear out. Carpets need replacing. Landscaping requires ongoing investment. Cost segregation captures this reality by reclassifying short-lived assets:
- 5-year property: Appliances, carpeting, decorative fixtures, certain electrical and plumbing components serving specific equipment (not the building overall), specialty flooring.
- 7-year property: Furniture, cabinetry, certain equipment and fixtures.
- 15-year property: Land improvements including landscaping, driveways, patios, decks, fences, sidewalks, outdoor amenities (fire pits, hot tubs mounted on concrete pads, pergolas).
For a furnished STR with outdoor amenities, 20-35% of the depreciable building value typically qualifies for reclassification. That percentage can be higher for well-appointed properties with significant landscaping, outdoor entertainment areas, and premium furnishings.
Bonus Depreciation: The Multiplier
Here's where the real power comes from.
Property reclassified into 5-year, 7-year, or 15-year categories qualifies for bonus depreciation. Under the Tax Cuts and Jobs Act and as permanently restored by the One Big Beautiful Bill Act (OBBBA) signed July 4, 2025, 100% bonus depreciation applies to qualifying property acquired and placed in service after January 19, 2025.
This means you can deduct the entire reclassified amount in year one. Not over 5 years. Not over 7 years. In year one.
The remaining building value (the portion not reclassified) still depreciates over 27.5 years at the standard straight-line rate.
Example: $500,000 purchase price. Land value: $75,000. Depreciable building: $425,000. Cost segregation identifies $110,000 in short-life assets (26%).
- Year 1 bonus depreciation: $110,000
- Year 1 straight-line on remaining $315,000 at 27.5 years: $11,455
- Year 1 total depreciation: $121,455 — before operating expenses
Add mortgage interest, property taxes, insurance, management fees, supplies, and cleaning costs, then subtract rental income, and you're looking at a total paper loss that could easily exceed $100,000 in year one on a mid-range STR.
The Bonus Depreciation Schedule (Historical Context)
The TCJA originally provided 100% bonus depreciation from 2017 through 2022, followed by a phase-down: 80% in 2023, 60% in 2024, 40% in 2025, 20% in 2026, 0% from 2027. The OBBBA permanently eliminated this phase-down. For qualifying property placed in service after January 19, 2025, the rate is 100% indefinitely.
| Tax Year | Bonus Depreciation Rate |
|---|---|
| 2023 | 80% |
| 2024 | 60% |
| 2025 (before Jan 20) | 40% |
| 2025 (after Jan 19) | 100% (OBBBA) |
| 2026 and beyond | 100% (permanent) |
If you placed property in service in 2023 or 2024, your bonus depreciation rate was locked at the rate for that year. The OBBBA doesn't retroactively change those rates. But improvements placed in service on or after January 20, 2025, qualify for 100%.
How the STR Loophole Makes It Work
Without the STR loophole (or Real Estate Professional Status), the large first-year loss created by cost segregation and bonus depreciation is passive. It can only offset passive income. For most high-income W-2 employees, there's no passive income to absorb it.
The STR loophole changes the classification. If your property meets the 7-day average stay rule and you materially participate, the activity is non-passive. The loss flows directly against your W-2 income.
At a 35% marginal federal rate, a $100,000 non-passive loss saves you $35,000 in federal taxes. That's the combined power of cost segregation and the STR loophole.
What a Cost Segregation Study Costs and Who Performs It
A quality cost segregation study for a residential STR typically costs $3,000–$6,000 depending on property size, complexity, and whether an in-person or remote inspection is required.
The study should be performed by an engineering or accounting firm that specializes in cost segregation — not a general CPA who offers it as an add-on service. Engineering-based studies with detailed component identification are most defensible under IRS scrutiny.
Ask your CPA for referrals to firms they've worked with, or look for firms that specifically advertise experience with short-term rentals and Section 168 property.
The "Look-Back" Study: Getting Caught Up
If you've owned your STR for years without a cost segregation study, you can still capture missed depreciation. A look-back study performs the analysis retroactively and allows you to catch up on all prior years' missed depreciation in a single tax year — without amending prior returns.
This is done through a change in accounting method (Form 3115) filed with your current-year return. The cumulative catch-up depreciation, called a Section 481(a) adjustment, is taken all at once. For a property owned for several years, this can generate a very large deduction in the year the study is completed.
Note: the look-back benefit applies to straight-line depreciation for the prior years. Bonus depreciation was only available in the year the property was placed in service, so you can't capture missed bonus depreciation through a look-back study.
Common Mistakes to Avoid
Getting a cheap "desktop" study. Some vendors offer cost segregation reports for $500–$1,000 based on generic property-type templates without inspecting your specific property. These reports are harder to defend under audit and may not accurately reflect your actual property components. An engineering-based, property-specific study is worth the investment.
Skipping the study entirely. Without cost segregation, you're depreciating everything over 27.5 years and leaving significant year-one deductions on the table. For properties valued above $200,000, the study ROI is typically 10-20x.
Getting the study after filing. Ideally complete the study before your first tax return for the property. If you miss year one, you can still do a look-back study, but you lose the bonus depreciation on those initial assets.
The Bottom Line: Cost segregation creates the losses. The STR loophole lets you use them. Together, they form one of the most powerful tax strategies available to real estate investors.
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