What a cost segregation study actually reclassifies: the 5-, 7-, and 15-year buckets in a residential rental.

Most people who ask about cost segregation already know the headline: a study lets you depreciate parts of a rental faster, which pulls deductions forward and lowers this year’s tax bill. What’s usually missing is the specific part — which parts of the building actually move, and where they move to. That’s the whole game. So here is the plain version: what leaves the 27.5-year clock, what buckets it lands in, and what never moves at all.

Why is a residential rental stuck on 27.5 years in the first place?

The tax code treats residential rental property as a single asset with a 27.5-year straight-line recovery period. Buy a $500,000 house to rent out, strip out the land, and the depreciable building gets deducted in equal slivers over 27.5 years — a little under 3.7% of the basis a year. That default is simple, and for a lot of owners it’s the only schedule their return has ever used.

The problem is that a building isn’t really one asset. It’s a structure wrapped around a lot of shorter-lived stuff: the carpet, the appliances, the cabinets, the driveway, the landscaping. None of those things last 27.5 years, and the IRS’s own cost segregation Audit Techniques Guide recognizes as much. A study is the engineering-and-accounting exercise of separating those components out and assigning each its correct, shorter recovery period.

What moves into the 5-year bucket?

The 5-year bucket is Section 1245 personal property — things that function more like equipment or furnishings than like the building itself. In a typical residential rental this is where the biggest reclassification usually comes from. Common examples: carpeting and other non-permanent flooring, appliances, cabinetry and countertops that aren’t structural, decorative and accent lighting, window treatments, and the specialty electrical or plumbing that serves specific equipment rather than the building as a whole. In a short-term rental the 5-year pile grows quickly, because the furniture and the guest-facing finishes all live here too. We wrote about the most-missed of those in the five short-life assets STR owners almost always under-claim.

What about the 7-year bucket?

Seven-year property shows up less often in a plain long-term rental and more often in furnished or short-term rentals. It covers certain furniture and fixtures that the code assigns a slightly longer class life than the 5-year items — think office-style furnishings and some equipment. For a lot of unfurnished single-family and small multifamily rentals, the 7-year bucket is thin or empty, and the real action is split between 5-year personal property and 15-year land improvements.

What lands in the 15-year bucket?

Fifteen-year property is land improvements: the things you built on the land that aren’t the land itself and aren’t part of the building. Driveways, walkways, patios, fencing, retaining walls, site lighting, and landscaping all qualify. These are technically Section 1250 property, but they carry a 15-year recovery period instead of 27.5, and they’re bonus-eligible, which matters a lot right now (more on that below). For properties on a real lot — a house with a driveway and a yard rather than a condo — the 15-year bucket can be a meaningful slice on its own.

What does a $500K rental look like once it’s reclassified?

Take a $500,000 single-family rental placed in service in 2026. Pull out the land — say the building is 80% of the price — and you’ve got $400,000 of depreciable basis that would otherwise crawl along at 27.5 years. A reasonable residential study reclassifies somewhere around 22% of that basis into the shorter buckets, so roughly $88,000 moves out of 27.5-year property and into 5-, 7-, and 15-year property.

Here’s where the timing rule earns its keep. Because 100% bonus depreciation was restored for property acquired after January 19, 2025, that entire $88,000 reclassified slice can be deducted in year one rather than spread across the shorter schedules. At a 32% marginal federal rate, deducting $88,000 up front is worth about $28,160 in first-year federal tax savings — before any state benefit. That’s the same building, the same purchase price; the only thing that changed is which components are sitting on which clock. How much of your price is land sets the ceiling on all of this, which is why the land allocation matters so much.

What never leaves the 27.5-year bucket?

Plenty. The structural shell stays put: framing, foundation, roof, exterior walls, windows, and the plumbing and electrical systems that serve the building as a whole rather than a specific piece of equipment. A study isn’t about relabeling the whole house as 5-year property — that’s the kind of aggressive move that turns a defensible study into a liability. The point is to move only what genuinely qualifies, document why, and leave the rest on 27.5 years where it belongs. Done that way, the result is audit-ready: every reclassified dollar traces back to a real component and a real basis, not a percentage someone pulled from a template.

If you’re trying to figure out whether the reclassifiable slice on your property is big enough to bother with, that’s exactly what a feasibility look answers. You can run rough numbers with our savings estimate, or tell us about the property and we’ll give you a candid read on whether a study pencils.