The 20–40% Rule: How Much of Your STR Property Qualifies for Accelerated Depreciation

If you've researched cost segregation, you've likely seen the "20–40%" figure cited as the typical reclassification range for investment properties. This number represents the share of a property's improvement value that gets moved from the 27.5-year or 39-year depreciation schedule into shorter-lived 5-, 7-, and 15-year categories. But what drives your property's result within that range — and when can it be even higher?

Understanding the Baseline: What's Always Structural

Some components will always remain on the long-lived schedule. The structural shell of a building — foundation, framing, load-bearing walls, roof structure, core plumbing, embedded HVAC, and permanent wiring — does not qualify for shorter depreciation lives regardless of what the property is used for. These are the components that define the building itself.

For a typical residential property, these structural components represent roughly 55–75% of improvement value. That leaves 25–45% as potentially reclassifiable — and this is why the 20–40% range exists, with actual results depending on property-specific characteristics.

The Seven Factors That Push Results Higher

1. Furnished vs. unfurnished at acquisition. This is the single biggest driver for STRs. A fully furnished Airbnb includes thousands of dollars in appliances, furniture, decorative lighting, and window treatments — all 5-year property. An unfurnished property sold at the same price has none of this personal property embedded in the purchase price.
2. Outdoor amenities. Pools, hot tubs, patios, decks, outdoor kitchens, fire pits, and extensive landscaping all qualify as 15-year land improvements. Properties with significant outdoor living spaces regularly push above 30% reclassification.
3. Recent renovations and upgrades. Properties that were renovated before sale often have newer appliances, updated fixtures, new flooring, and refreshed interiors — all components that may have a higher cost basis allocated to personal property.
4. Property type and use. Short-term rentals, hotel-to-condo conversions, and properties with commercial kitchens or dedicated entertainment spaces have higher concentrations of personal property than plain residential homes.
5. Custom or high-end finishes. Properties with specialty millwork, decorative tile, custom cabinetry (removable), and upscale lighting have more identifiable personal property than standard-finish properties.
6. Garage or storage structures. Detached structures, carports, sheds, and outbuildings are often accounted for separately and may have different depreciation treatment from the main structure.
7. Age of the property. Older properties sometimes have higher land improvement percentages due to mature landscaping and dated outdoor infrastructure that gets correctly identified as 15-year property.

What a Range of Results Looks Like

What Happens When Furnishings Are Allocated in the Purchase Agreement

If the purchase agreement separately identifies the value of personal property included in the sale (furniture, appliances, etc.), that allocation is directly documented and generally accepted by the IRS. Some sellers resist this because it creates ordinary income for them on the personal property portion. If no allocation exists, the cost seg study must estimate the personal property's fair market value at the time of acquisition — which is entirely allowable but requires a supportable methodology.

The Relationship Between Reclassification Rate and Tax Savings

With 100% bonus depreciation permanent under OBBBA, every dollar of reclassified 5-year or 15-year property is deducted in full in year one. The relationship between reclassification rate and tax savings is direct and immediate. On a $500,000 property improvement basis:

• 20% reclassification = $100,000 additional year-1 deduction = $37,000 savings (37% bracket)
• 30% reclassification = $150,000 additional year-1 deduction = $55,500 savings (37% bracket)
• 40% reclassification = $200,000 additional year-1 deduction = $74,000 savings (37% bracket)

This is why the characteristics of your specific property matter so much. A furnished lakefront cabin with a pool and extensive deck might generate nearly double the deduction of an unfurnished condo at the same purchase price.