When you purchase, build, or remodel a building, the tax rules do not always treat every part of that property the same way. Some costs may be tied to the building structure itself, while others may relate to assets that wear out, get replaced, or serve a more specialized business function.

That is where a cost segregation study can make a meaningful difference.

A cost segregation study helps separate a property into its proper tax “buckets” so depreciation can be calculated more accurately. The IRS describes cost segregation as the allocation, or reallocation, of a property’s total cost or value into the appropriate property classes and recovery periods for depreciation purposes.

In everyday terms: instead of depreciating the entire building over a longer period, a cost segregation study may identify certain components that can be depreciated over shorter periods. For example, the IRS notes that nonresidential real property is generally depreciated over 39 years and residential rental property over 27.5 years, while certain tangible personal property, such as equipment, furniture, and fixtures, may have shorter recovery periods, such as 5 or 7 years.

 

Why This Matters

The benefit is usually about timing. Cost segregation does not create a new deduction out of thin air. It may, however, help move certain depreciation deductions into earlier tax years.

For business owners and real estate investors, that timing can matter. Accelerated deductions may reduce current taxable income, improve cash flow, and create more flexibility to reinvest in operations, people, property improvements, or debt reduction.

This planning opportunity is especially important under current depreciation rules. The IRS issued guidance on the permanent 100% additional first-year depreciation deduction for eligible depreciable property acquired after January 19, 2025, under the One Big Beautiful Bill. Section 179 limits have also increased for tax years beginning in 2026, with a maximum deduction of $2,560,000 that begins phasing out when qualifying property placed in service exceeds $4,090,000.

 

Who Should Consider a Cost Segregation Study?

A cost segregation study may be worth a closer look if you have recently:

Purchased a commercial or residential rental property; built a new facility; completed a renovation, expansion, or remodel; or made significant leasehold or property improvements.

It may also be useful for property you already own. The IRS Cost Segregation Audit Technique Guide notes that a taxpayer may conduct a cost segregation study on used or previously existing property and then recompute depreciation deductions for prior years. In those cases, a change in accounting method may be required. IRS Form 3115 is used to request a change in an overall accounting method or in the accounting treatment of an item, including certain depreciation changes.

 

Quality Matters

Cost segregation is not a “back of the napkin” exercise. The IRS emphasizes that asset classification is fact-specific and that there are no bright-line tests for separating certain personal property from real property.

A quality study should do more than estimate a tax benefit. It should identify the property, classify assets into the correct property classes, explain the tax rationale, substantiate cost basis, and reconcile allocated costs to actual costs. The IRS also outlines 13 principal elements of a quality cost segregation study, including experienced preparers, appropriate documentation, legal analysis, cost reconciliation, and consideration of related tax issues.

In other words, the goal is not just to maximize deductions. The goal is to pursue the best available tax result within the framework of the law, supported by strong documentation and thoughtful planning.

 

A Few Planning Considerations

Cost segregation can be powerful, but it is not one-size-fits-all. Your actual benefit depends on your income, ownership structure, passive activity limitations, at-risk rules, future sale plans, and broader tax strategy. IRS Publication 925 explains that passive activity and at-risk rules may limit the amount of deductible loss from a trade, business, rental, or other income-producing activity.

There may also be future tax considerations when the property is sold. IRS Publication 544 explains that when depreciable property is sold at a gain, part or all of the gain may be treated as ordinary income under depreciation recapture rules.

That is why cost segregation should be part of a broader tax conversation, not just a standalone report.

The Abacus! Perspective

We believe good planning gives you confidence. You should understand what the numbers mean, how they affect your unique situation, and what decisions are available before tax time arrives.

If you have purchased, built, or improved real estate, a cost segregation study may be worth discussing. Our team of Abacus! Professionals can help you evaluate the opportunity, coordinate with qualified specialists, and determine whether the strategy fits your overall tax plan.