If your business owns the building it operates out of (a shop, a restaurant space, a retail storefront, or a manufacturing facility), a cost segregation study is one of the most underused tax strategies available to you. It takes a building you’re already depreciating over 39 slow years and finds the pieces the tax code actually lets you write off in five, seven, or fifteen. Combined with 100% bonus depreciation, now permanent, that can mean a six-figure deduction in a single tax year instead of a trickle spread across three decades.
When you buy or build a commercial building, the default tax treatment lumps the entire cost into one bucket depreciated over 39 years (27.5 years for residential rental property). But a building isn’t really one asset. It’s dozens of distinct components: electrical wiring dedicated to production equipment, specialized plumbing, decorative finishes, carpet and cabinetry, parking lots and landscaping, and more.
A cost segregation study is an engineering-based analysis that identifies which components of your building can legally be reclassified into much shorter depreciation schedules, typically 5, 7, or 15 years, rather than the standard 39. The IRS’s own Cost Segregation Audit Techniques Guide lays out exactly how these studies should be prepared and documented, which tells you two things: it’s a legitimate, well-established strategy, and it needs to be done correctly to hold up.
Reclassifying building components into shorter life spans has always accelerated deductions. But the math changed dramatically with the One, Big, Beautiful Bill, which permanently restored 100% bonus depreciation for qualifying property acquired after January 19, 2025. The IRS issued implementing guidance on this in Notice 2026-11.
Here’s why that combination matters: property with a depreciable life under 20 years generally qualifies for bonus depreciation. Once a cost segregation study moves a meaningful share of your building into those shorter categories, that entire reclassified amount can potentially be deducted in the very year you place the property in service, not gradually over 5, 7, or 15 years, and with no dollar cap. For a building purchase or major renovation, that can mean a deduction large enough to fully offset a profitable year.
Cost segregation gets pitched heavily to real estate investors, and it does make sense there. But it’s just as relevant for:
That last group is worth calling out specifically. We work with many owners who run a contracting or manufacturing business alongside a real estate entity that holds the building, sometimes leased back to their own operating company. A cost segregation study on the holding entity’s property can generate substantial paper losses, but those losses need to be evaluated against passive activity rules before you assume they’ll offset your operating income. This is exactly the kind of structuring question worth working through with your tax planning team before you commission a study, not after.
An engineering-based cost segregation study isn’t free, and it isn’t right for every building. A quick feasibility analysis, comparing your building’s cost basis, age, and use against the potential reclassification, can tell you whether a full study is likely to pay for itself before you commit to one. Newer construction and recent purchases or renovations tend to have the most upside, since more of the original cost documentation is available and intact.
Cost segregation is powerful, but it comes with real considerations:
When you eventually sell the property, some of the accelerated depreciation may be recaptured and taxed at a less favorable rate. This doesn’t erase the benefit, but it should factor into your long-term exit planning.
The IRS’s audit guide is explicit about what a defensible study looks like. A sloppy or unsupported reclassification is an audit risk, not a tax strategy.
As noted above, if the building sits in a separate entity from your operating business, make sure the losses are actually usable against your income before you count on them.
If your business owns its building, or you’re structuring a real estate holding entity alongside an operating company, a cost segregation study paired with current bonus depreciation rules could be one of the largest single deductions available to you this year. Book a 30-minute call with our team, and we’ll take a first look at whether the numbers work for your property before you spend a dollar on a full study. Have a quick question first? Start a conversation here.
This article is for general informational purposes only and is not tax advice. Cost segregation studies and bonus depreciation rules are complex and fact-specific; please consult a qualified tax professional about your situation.
Christine Gervais
Christine Gervais is a licensed CPA, using her skills to help businesses grow and achieve their fullest potential. Christine has a Master’s degree in accounting from Southern New Hampshire University in addition to holding her CPA license for over a decade. Notably, Christine is a nationally recognized speaker providing education to other CPAs on how to best serve clients as well as instruction on a wide variety of topics for business owners on how to maximize success. Christine prides herself on the value she can bring to clients with her extensive tax knowledge and provides strategic, forward-thinking financial strategies to help clients grow. When not behind her desk, you can find Christine spending quality time with her daughter and stepson or tending to the family’s excessively loved farm animals.
