Cost Segregation for Multifamily STR Properties: Duplexes, Triplexes & Small Apartments

Multifamily STR investing — buying duplexes, triplexes, or 4–8 unit buildings and listing all units on Airbnb or VRBO — has grown dramatically as investors look to maximize income per square foot in high-demand vacation markets. These properties are fully eligible for cost segregation, and the analysis benefits from a larger depreciable base spread across multiple high-income-producing units.

How Cost Segregation Works for Multifamily

A cost segregation study on a multifamily property analyzes the building as a whole — structural systems, common areas, and individual unit components — then allocates costs. Personal property components (furniture, appliances per unit) and land improvements (parking, landscaping, outdoor common areas) are broken out and given their respective shorter depreciation lives.

The STR Loophole in a Multifamily Context

For each unit operating as an STR (average stay 7 days or fewer), the allocated depreciation losses can offset ordinary income if you materially participate. In a 4-unit building where all 4 units are Airbnb-listed, the entire allocated improvement basis qualifies for STR treatment. This is a powerful combination with cost segregation — especially at higher property values.

Common Area Depreciation in STR Multifamily

Shared outdoor areas — parking lots, landscaping, outdoor seating, lighting, pool — are all 15-year land improvements. In a 4-unit STR building with a shared pool and parking area, these common-area improvements add significantly to the reclassifiable base. A $50,000 shared pool is a $50,000 deduction at 100% bonus depreciation.