Can You Do Cost Segregation on a Duplex or Small Multifamily Property?

One of the most common misconceptions about cost segregation is that it's only for large commercial buildings or apartment complexes. It's not. Duplexes, triplexes, fourplexes, and small multifamily properties can all benefit — and for investors in the $300,000 to $1,500,000 range, the economics often make a lot of sense.

Here's what you need to know.

The basics haven't changed

Cost segregation works the same way regardless of property type. An analysis identifies components of your building that qualify for 5-year or 15-year depreciation rather than the standard 27.5-year residential schedule. Those accelerated deductions front-load your tax savings into the early years of ownership.

What changes by property type is the mix of components typically present and the percentage of the depreciable basis that gets reclassified.

How small multifamily properties compare

A single-family rental or STR might have unique specialty components — a pool, outdoor kitchen, smart home system — that push reclassification rates higher. Small multifamily properties typically don't have those amenities per unit, but they make up for it in volume and in shared-use components.

A fourplex, for example, will have:

• Carpet and flooring across four units (5-year)
• Appliances in each unit — refrigerators, ranges, dishwashers (5-year)
• Shared parking areas and walkways (15-year)
• Landscaping and site improvements (15-year)
• Laundry equipment if shared (5-year)
• Individual HVAC systems or window units depending on configuration (varies)

The reclassification rate for a standard small multifamily property typically falls between 12% and 22% of the depreciable basis — lower than an amenity-heavy STR, but still substantial.

Running the numbers on a duplex

Let's say you purchased a duplex in 2025 for $450,000. After subtracting land value (assume 20%), your depreciable basis is $360,000.

A cost segregation study identifies 15% of that basis — $54,000 — as 5-year and 15-year property eligible for immediate bonus depreciation.

At a 32% federal tax bracket, that's $17,280 in year-one tax savings from a study that costs $1,197. That's a 14x return before the study even accounts for the accelerated deductions in years two through five.

The look-back opportunity

If you purchased a duplex or small multifamily property in a prior tax year and never did a cost segregation study, you may be able to capture those missed deductions now through a look-back study and a Form 3115 filing.

This allows you to take a catch-up deduction in the current tax year for all the accelerated depreciation you missed in prior years — without amending past returns. For a property held several years, that catch-up amount can be significant.

When it doesn't make sense

Cost segregation has a minimum viable property value. For properties under $200,000, the math often doesn't work — the study cost approaches or exceeds the tax benefit. For properties between $200,000 and $350,000, it depends heavily on your tax bracket and whether the property has above-average specialty components.

The clearest wins are properties over $400,000 with investors in the 32% bracket or higher.

Getting an estimate

The fastest way to know if your duplex or small multifamily property is a good candidate is to run a free savings analysis. You'll get a personalized estimate based on your property type, purchase price, state, and tax bracket — no commitment, no email pitch sequence, just the numbers.