Cost segregation is an engineering-based study that looks at the individual components of a building and reclassifies them into shorter depreciation schedules. Instead of depreciating the entire property over 27.5 years for residential or 39 years for commercial, certain components get moved into 5-year, 7-year, and 15-year categories.

The components that get reclassified include things like certain electrical systems, plumbing, carpeting, cabinetry, parking lots, landscaping, and site improvements. Under a standard depreciation approach, these items get grouped with the building for convenience. But they have shorter useful lives and can be separated out with a proper study.

The big benefit comes from bonus depreciation. Components in these shorter-lived categories qualify for 100% bonus depreciation, which means you can take the entire deduction in the year the property is placed in service rather than spreading it out over decades. For a $2 million commercial property, a cost segregation study might identify $400,000 or more in components that can be written off immediately instead of over 39 years.

Is it worth it? That depends on two main factors.

First, property size matters. Cost segregation studies have a cost, typically ranging from a few thousand dollars for smaller properties to $15,000 or more for larger ones. The deduction benefit needs to exceed the study cost by a meaningful margin. For most investors, the sweet spot starts around $500,000 to $1 million in building value, though this varies based on the property type and how much can be reclassified.

Second, you need to be able to use the deductions. Real estate depreciation creates losses that are typically passive, meaning they can only offset passive income unless you qualify as a real estate professional or the property qualifies as a short-term rental with material participation. If you have plenty of passive income from other rentals, the deductions have immediate value. If your passive losses already exceed your passive income, accelerating more depreciation might just build up suspended losses that sit unused until you sell.

For investors managing portfolios with real estate fund accounting needs across multiple properties and entities, cost segregation becomes one piece of a larger depreciation strategy that should be planned across the whole portfolio rather than property by property.

The study itself is performed by engineers or specialized firms, but it needs to coordinate with your overall tax approach. That is where working with someone who understands real estate tax planning becomes important. A cost segregation study in isolation might generate impressive numbers on paper, but whether those numbers translate to actual tax savings depends on your specific situation, your other income sources, and whether you can actually absorb the deductions in the year you need them.