When a cost segregation study looks at your rental, it's doing one specific thing: pulling components out of the default 27.5-year depreciation bucket and moving them into shorter 5-, 7-, and 15-year buckets. Those shorter buckets are where all the acceleration comes from. But what actually belongs in each bucket on a residential rental? This guide walks through the IRS recovery periods, the specific components that typically qualify for each on residential properties, and why documentation matters for every one of them.
Quick refresher: what the buckets mean
Under MACRS (Modified Accelerated Cost Recovery System), the IRS assigns property to specific asset classes based on its expected useful life. For residential rental property, the relevant classes are:
- 5-year property: Personal property and short-lived assets inside the building. Depreciated over 5 years on a 200% declining balance method.
- 7-year property: Specialized items with slightly longer useful lives. Depreciated over 7 years, also 200% declining balance.
- 15-year property: Land improvements — assets that sit outside the building shell but aren't the land itself. Depreciated over 15 years on a 150% declining balance method.
- 27.5-year property: The building structure and integrated systems. Depreciated straight-line over 27.5 years. This is the default bucket for any rental property without a cost segregation study.
Importantly, the 5-, 7-, and 15-year buckets all qualify for bonus depreciation (which is 100% in 2026 for qualifying property acquired after January 19, 2025). The 27.5-year building shell does not.
What's in 5-year property on a residential rental
5-year property is where most of the reclassification value tends to come from. On residential rentals, it typically includes:
- Carpet and other removable flooring. Carpet has a short useful life and is specifically identified as 5-year property in IRS guidance.
- Appliances. Refrigerators, dishwashers, ranges, washers, dryers — these are 5-year property whether they came with the property or were installed later.
- Decorative and removable millwork. Built-ins that aren't structurally integrated, decorative trim, and some cabinetry.
- Window treatments. Blinds, curtains, and other non-integrated window coverings.
- Furniture (on furnished rentals). This is the big one for short-term rentals. Beds, sofas, dining sets, tables, lamps, linens, kitchen equipment, decor — all 5-year property, and all fully deductible in Year 1 under 100% bonus.
- Certain plumbing and electrical serving specific equipment. For example, dedicated wiring or plumbing serving a specific 5-year asset can sometimes follow that asset's classification. Facts matter here.
- Decorative light fixtures. Decorative (rather than general illumination) fixtures may be 5-year property.
On a typical unfurnished long-term rental, 5-year property might represent 6–10% of the building basis. On a well-furnished short-term rental, it can easily reach 20–25%.
What's in 7-year property
7-year property is a smaller and narrower category on residential rentals. It typically includes:
- Office furniture and equipment. If your rental has a dedicated office area for rental management.
- Certain specialty items that don't fit cleanly into 5-year or 15-year categories.
On most residential rentals, 7-year property is a very small piece of the overall reclassification — often zero. It's more common on specialized properties or commercial assets. Don't expect a large 7-year allocation on a standard single-family rental.
What's in 15-year property: land improvements
This is the second-biggest category on most residential rentals. 15-year property covers "land improvements" — things that sit outside the building but aren't the raw land itself:
- Driveways, walkways, and parking areas. Asphalt, concrete, pavers.
- Fencing. Wood, metal, vinyl — any type.
- Landscaping. Trees, shrubs, turf, irrigation systems, landscape lighting. Plantings count even though they're alive.
- Retaining walls. Often a large chunk of basis on hillside properties.
- Exterior lighting. Site lighting, pathway lighting, porch lights that aren't integrated into the structure.
- Site drainage. French drains, catch basins, grading.
- Outdoor amenities. Patios, decks (if not structurally integrated), fire pits, pergolas, outdoor kitchens.
- Pool, spa, and related equipment. The pool shell itself is usually 15-year, as is pool equipment.
- Concrete pads. HVAC pads, trash enclosure pads, utility pads.
15-year property typically represents 5–15% of building basis on a residential rental, though this varies significantly with the property. A hillside home with retaining walls and landscaping might see much more; a simple rancher on a flat lot might see less.
What stays in 27.5-year property
Even with a cost segregation study, the bulk of most residential rentals stays in the 27.5-year bucket. That's:
- Framing, studs, roofing, exterior walls
- Windows and doors that are structurally integrated
- Interior structural walls
- General plumbing (main lines, branch lines, fixtures that serve the whole building)
- General electrical (main panel, branch circuits, lighting that provides general illumination)
- HVAC systems (furnace, central air, ductwork)
- Built-in cabinetry that's structurally integrated
- Tile, hardwood, and other hard surface flooring that's affixed to the structure
For most residential rentals, the 27.5-year bucket ends up with 70–90% of the building basis after a cost segregation study. That's expected. The value comes from the 10–30% that gets pulled out, not from reclassifying the whole building.
How the allocations are actually determined
This is the part that separates a real engineering-based study from a cheap spreadsheet tool. Proper classification requires:
- Property-specific observation. Photos of each room, finishes, appliances, fixtures, flooring, cabinetry, and the exterior. The engineer needs to see what's actually there.
- Cost basis methodology. For each identified component, allocate a portion of the building basis using a documented method (typically the Residual Estimation Method with RCNLD calculations).
- Consistency with IRS guidance. Every classification has to align with the categories the IRS publishes in the Cost Segregation Audit Techniques Guide.
- Supporting documentation. Each category in the report should reference the evidence that supports it — photos, invoices, surveys, or public records.
A DIY tool that skips any of these steps is just applying ZIP-code averages to your property, which produces less defensible classifications and usually a more conservative result.
Why documentation matters so much for these classifications
If the IRS ever examines your return, the first thing they'll ask about isn't whether cost segregation is legal (it is, explicitly). They'll ask whether the specific classifications on your property are supported. That means:
- Is there photo evidence showing the 5-year flooring is actually carpet, not hardwood?
- Is there documentation showing the 15-year site improvements actually exist?
- Is the methodology for allocating cost basis across categories written down and consistent?
- Does the report tie cleanly to the return and the property records?
A quality report answers all of these before the question is asked. This is why audit support and quality review matter — and why a single-page summary or generic spreadsheet won't protect you.
The short version
A cost segregation study on a residential rental typically reclassifies 10%–35% of the building basis into 5-, 7-, and 15-year property. The 5-year bucket is mostly appliances, removable items, and (for furnished rentals) everything inside. The 15-year bucket is site improvements and landscaping. 7-year is usually a small piece. The building shell stays 27.5-year.
The specific numbers on your property depend on the type, finish level, whether it's furnished, and what's outside. Use the free cost segregation calculator to see a property-specific estimate in under a minute.