Every year you own a commercial property without a cost segregation study is a year of deductions pushed into the future. The study does not create new deductions. It moves depreciation you are already entitled to into the years when you can use it most, so you owe less tax now.
This post explains why the year you buy is usually the best time to order a study, what changes if you wait, and how a look-back study works if you already own the building.
What a Cost Segregation Study Actually Does
When you buy a commercial building, the IRS default is to depreciate the entire structure over 39 years. That works out to roughly 2.6% of your cost basis each year, spread evenly for nearly four decades.
A cost segregation study breaks that basis apart. A licensed engineer reviews the property, including construction documents and a site visit when needed, and identifies components that qualify for shorter schedules under IRS guidelines. Specialty electrical, plumbing, flooring, cabinetry, parking lots, and other land improvements often qualify for 5-, 7-, or 15-year treatment instead of 39 years.
The study accelerates deductions you already have. The question is whether you take them now or spread them over decades.
Why the Acquisition Year Is the Best Time
Three things line up in the year you buy.
1. 100% bonus depreciation applies to the reclassified components
Bonus depreciation lets you deduct qualifying property in the year it is placed in service. Under the 2025 tax law (Public Law 119-21), 100% bonus depreciation is permanent for qualifying property acquired and placed in service after January 19, 2025. When a study reclassifies components into 5-, 7-, or 15-year property, those components can be deducted in full in year one.
| Placed in service | Bonus rate | Effect on a cost seg study |
|---|---|---|
| 2022 | 100% | Reclassified components deducted in full in year one |
| 2023 | 80% | 80% of reclassified components deducted in year one |
| 2024 | 60% | 60% deducted in year one |
| Acquired before January 20, 2025, placed in service in 2025 | 40% | 40% deducted in year one |
| Acquired and placed in service after January 19, 2025 | 100%, permanent | Reclassified components deducted in full in year one |
For a property bought today, the rate is not going down. The reason to act in the acquisition year is cash flow, not a shrinking deadline.
2. Documentation is cleanest at acquisition
At acquisition, construction documents, cost allocation records, and the purchase price are fresh and easy to work with. Three years later, some of those records may be harder to find, and renovations can blur the original picture. The study can still be done, but it takes more work.
3. The time value of money
A dollar of deduction this year is worth more than the same dollar five years from now. Accelerating $400,000 of deductions into year one lowers your tax bill now and frees up cash you can put back into the property or the business. Waiting five years means that cash sits with the government instead.
The Look-Back Study: Same Rules, Later Timing
If you already own the building, a look-back study still works. The IRS allows catch-up depreciation through an accounting method change on Form 3115. All of the depreciation you missed in prior years is claimed in the current year, and no amended returns are filed.
The bonus rate on a look-back follows the year the property was placed in service, not the year you do the study. A building placed in service in 2022 still gets the 100% rate that applied in 2022. One placed in service in 2023 gets 80%.
What you give up by waiting is time. The deductions you could have taken years ago arrive in one catch-up year instead, and you have carried the extra tax in the meantime.
What This Means If You Recently Bought
If you bought commercial real estate in the last year and have not ordered a study, now is the time to price one. A study filed with the acquisition-year return puts the full benefit into your first year of ownership.
If you bought in a prior year, the look-back is still worth reviewing. One method change captures the missed depreciation without amended returns.
Keep in mind that accelerated depreciation can be recaptured when you sell, so the strategy works best on property you plan to hold. Your CPA should model the passive loss rules and your holding period before you commit.
Studies through Opscale Exchange are a flat fee starting at $3,500, quoted after a free review. The review shows what your property looks like under each scenario before you spend anything.