Residential vs commercial depreciation

The building itself, the part a cost-segregation study does not reclassify, runs on one of two clocks. Residential rental property depreciates over 27.5 years. Commercial property depreciates over 39. That eleven-and-a-half-year gap decides how much you deduct every single year you own the place, so it is worth knowing which side of the line your property sits on, and why the line is not always obvious.

Why the two clocks exist and what they do

The tax code treats a home people live in differently from a building where business happens. Residential rental property, apartments, single-family rentals, most short-term rentals, gets the shorter 27.5-year recovery period. Everything else, offices, retail, warehouses, industrial, gets 39 years.

Shorter clock, bigger yearly deduction. Take a building worth $800,000 after carving out land. On the 27.5-year residential clock, that is about $29,000 of depreciation a year. On the 39-year commercial clock, the same $800,000 gives about $20,500 a year. Same building cost, roughly $8,500 more deduction every year on the residential side, purely because of which clock applies.

The residential clock is shorter, so the same building throws off a larger deduction every year on the residential side than the commercial side.

Land is the number that comes first

Before either clock starts, one thing has to be settled: how much of your purchase price is land. Land never depreciates, on either clock, ever. So the first move on any property is splitting the price into land and building, and the split matters enormously, because every dollar you can reasonably assign to the building is a dollar you get to depreciate, and every dollar stuck in land is a dollar you never deduct until you sell.

This is where a defensible allocation earns its keep. Many owners default to the county assessor’s land-to-building ratio, but that ratio is often unfavorable and is not the only supportable method. A cost-segregation study, or a proper appraisal, can support a more accurate split, and on some properties that alone is worth the effort before you even get to reclassifying components.

Every dollar you assign to land is a dollar you never depreciate, so the land-to-building split is the first and most permanent depreciation decision you make.

What actually sits on the line

The 27.5-versus-39 question sounds settled until a property does not fit neatly in one box, and several common ones do not.

A short-term rental is the sharpest example. A property you rent by the night can be treated as commercial, 39-year property, rather than residential, if the average guest stay is short enough and services resemble a hotel. That is the opposite of what most owners assume, and it interacts with the short-term-rental rules in ways that reach well beyond depreciation.

Mixed-use buildings, a storefront with apartments above, split between the two clocks based on how the space is used and how the income breaks down. And a building’s use can change: convert an office to apartments and the clock that applies can change with it. None of these are edge cases you can eyeball. They are the reason the residential-versus-commercial call belongs with a tax advisor and, often, a cost-segregation study that documents the split.

The seam most owners miss

Here is the crossover that a depreciation-only view hides. The residential-versus-commercial clock only governs the building, the part left after a cost-segregation study pulls out the fast components. So the two decisions compound. A study moves 5, 7, and 15-year property into the fast buckets, and whatever building remains runs on its 27.5 or 39-year clock. On a commercial property, where the base clock is the slow 39-year one, the value of a study is actually larger, because the alternative to reclassifying is that slow 39-year drip. The slower the base clock, the more a study is worth.

The slower a building’s base clock, the more a cost-segregation study is worth, which is why studies often pay off best on 39-year commercial property.

The bottom line

• Residential rental property depreciates over 27.5 years; commercial over 39.
• The shorter residential clock produces a larger annual deduction on the same building cost.
• Land never depreciates, so the land-to-building split is the first and most permanent decision.
• Short-term rentals, mixed-use, and converted buildings do not always sit where you expect.
• The slower the base clock, the more a cost-segregation study is worth, favoring commercial property.

To see how a study reclassifies the rest of the building, read what is cost segregation. For the full picture, start at the depreciation and cost segregation hub.

Last verified August 2026.