Short answer

Apartment buildings are where cost segregation earns its reputation. A multifamily property is residential rental property, so the building is depreciated over 27.5 years, but a large share of what an owner paid for is not the building: parking, site lighting, fencing, drainage and landscaping are 15-year land improvements; appliances, carpeting, window coverings, laundry equipment, fitness and office equipment, and furnishings in common areas or furnished units are 5- or 7-year property. Site work and unit contents scale with the number of units, so the reclassified amount is usually larger, in dollars and as a share of basis, than for a house. The same limits still apply: the deduction is only timing, the passive activity rules decide whether you can use it, and recapture waits at sale. This article covers what a study finds in a multifamily building, the evidence it needs, how portfolios are handled, and the decisions around it. It is general education, not tax advice.

What a study finds in an apartment building

Component groupClassExamples
LandNot depreciableThe site; grading and clearing that is part of the land
Structure and building systems27.5-yearFoundations, framing, roof, exterior, general electrical, plumbing and HVAC serving the building, elevators, stairs
Land improvements15-yearParking lots and drives, curbs, sidewalks, site lighting, fencing, retaining walls, storm drainage, pool decks, depreciable landscaping
Unit contents and equipment5-yearAppliances, carpeting, window treatments, furniture in furnished units, laundry equipment, fitness and clubhouse equipment
Business-function systems5- or 7-year on their factsDedicated electrical and plumbing serving equipment rather than the building, certain signage, security and access systems on their facts

Classification is item by item on function and the law, the approach the Tax Court took in Hospital Corporation of America. The rows are where the questions usually land, not answers for your building.

Why multifamily changes more than a house

  • Site work scales. Parking for fifty units, lighting, drainage, fencing and grounds are substantial 15-year property. A house has a driveway.
  • Unit contents repeat. Fifty sets of appliances and fifty units of flooring add up.
  • Common areas add equipment. Laundry rooms, fitness centers, leasing offices, pools and clubhouses carry equipment and finishes that serve a business function.
  • Land share is often lower as a fraction of the price than for a house on a suburban lot, so the depreciable pool is larger.

The result is that a well-evidenced multifamily study usually reclassifies a meaningful share of basis, which is why the passive activity and recapture questions matter more, not less: the numbers are bigger in both directions.

The residential test still applies

An apartment building is residential rental property only if 80 percent or more of its gross rental income comes from dwelling units. Mixed-use buildings with ground-floor retail, or buildings with substantial short-term or corporate housing, can fail the test and become 39-year nonresidential property. The study records the facts; the adviser makes the call. The classification of the building does not change the classification of the land improvements or the personal property, but it changes how much of the remainder is locked in the slowest class.

Evidence for a multifamily study

Everything in the general evidence article, with emphasis on:

  • Construction records for new builds and renovations: schedules of values, pay applications, change orders, subcontractor invoices by trade. Indirect costs such as design fees, permits and general conditions are capitalized under section 263A and allocated across components by a stated method.
  • Site drawings for the land improvements, which are often the largest reclassification.
  • Unit inventories and appliance schedules.
  • Rent rolls and leases, for the residential test and the placed-in-service date.
  • Prior studies and schedules if the property was bought from an owner who had one.

A site visit is the norm for a building of any size; a study of an apartment complex without one should explain itself.

Portfolios and sampling

For an owner with many similar buildings, the IRS guide describes sampling or modeling approaches under conditions, with documentation of the sample design and its application. This is a statistical method applied to a population, not a percentage applied to one property, and it needs a practitioner who can document it. Ask how the sample was drawn, how results were extrapolated and how the approach is disclosed in the report.

The decisions around the study

  1. Can the owner use the loss? For an individual, rental losses are generally passive; the special allowance phases out between $100,000 and $150,000 of modified adjusted gross income, and real estate professionals are treated differently. For a partnership or syndication, the loss passes through to partners, each of whom faces the rules on their own return; a separate article covers syndications.
  2. Acquisition date. For qualified property acquired after January 19, 2025, the 5-, 7- and 15-year property may be expensed in full under the permanent 100 percent rule; earlier acquisitions stay on the phase-down.
  3. Exit. Multifamily is traded. Recapture on the reclassified property at ordinary rates, and unrecaptured section 1250 gain at up to 25 percent on the building, arrive at sale; like-kind exchanges and hold periods are planning questions for the adviser.
  4. Renovations. Value-add plans create separate assets with their own dates and classes, and dispositions of replaced components.
  5. State. Ask.

Common errors in multifamily studies

  • Treating the whole site as land, or the whole site as land improvements.
  • Classifying building-wide electrical and plumbing as personal property without the function analysis.
  • Counting unit appliances from a rent roll instead of an inventory.
  • Ignoring the residential test on a mixed-use building.
  • Applying a percentage from another property, which the IRS guide treats as the least reliable approach.

What people ask on Reddit and other forums

Multifamily owners and syndication investors dominate the "cost segregation reddit" threads on r/realestateinvesting. The searches that lead people to these threads are usually phrased "cost segregation apartment building", "multifamily cost segregation" and "cost segregation duplex fourplex".

"Is a fourplex worth studying?" It is residential rental property like a house, with more units and often more site work. Run the five checks; the fee is spread over more contents than a single house has.

"The syndication's K-1 shows a huge loss. Can I use it?" Only under your own passive activity position. The loss passes through; the rules apply on your return.

"We're doing a value-add renovation. Study before or after?" Both events matter: the acquisition study covers the building as bought; the renovation creates new assets with their own dates. Talk to the adviser about sequencing and about dispositions of replaced components.

"Mixed-use with retail downstairs. Still 27.5?" Only if 80 percent or more of gross rental income is from dwelling units. Otherwise the building is 39-year property.

Questions people also ask

What percentage of an apartment building can be reclassified?

There is no answer that applies to your building. Site work, unit contents, common-area equipment and the land share differ property by property. A study produces the figure; a quoted percentage is an average of other buildings.

Is an apartment building 27.5-year or 39-year property?

27.5-year if 80 percent or more of gross rental income comes from dwelling units; otherwise 39-year. Mixed-use and transient-heavy buildings need the test applied on the facts.

Does bonus depreciation apply to the building?

No. It applies to the 5-, 7- and 15-year property a study identifies, at 100 percent for qualified property acquired after January 19, 2025.

Can one study cover several buildings?

Yes, either building by building or, for many similar properties, by a documented sampling or modeling approach that the IRS guide describes under conditions.

What is the biggest single reclassification in most apartment studies?

Usually the site improvements: parking, drives, lighting, fencing, drainage and grounds. Unit contents follow.

Sources