Every year, thousands of real estate investors learn about cost segregation for the first time, years after their acquisitions closed. They hear about accelerated depreciation at a conference, in a podcast, or from a CPA who finally brings it up. And the first question is almost always the same: Is it too late?
For most investors who acquired property after September 2017, the answer is no. A lookback cost segregation study allows property owners to recapture missed depreciation without amending prior year tax returns – a distinction that surprises nearly everyone who encounters it.
What Is a Lookback Cost Segregation Study?
A lookback study applies the same engineering-based analysis used in a standard cost segregation study, but to a property that has already been depreciating on a straight-line schedule for several years. The goal is to identify short-life assets – site improvements, removable flooring, decorative lighting, appliances – that should have been classified separately and depreciated on an accelerated timeline.
The critical mechanism is IRS Form 3115, a change of accounting method filing. Rather than going back and amending each prior year’s return individually, the investor files the 3115 and captures the cumulative missed depreciation through what’s called a Section 481(a) adjustment. The entire benefit lands on the current tax year’s return.
Brian Kiczula, founder of Sarasota-based cost segregation firm CostSegRx, notes that investors often assume they’ll have to amend prior year returns. That’s not the case. The missed depreciation is pulled forward using the 481(a) adjustment and shows up on the current year’s filing. “You don’t have to go back,” Kiczula says. “It all comes through on this year’s return.”
Can You Still Do a Cost Segregation Study on an Older Property?
There is an important exception that many investors and even some tax professionals overlook: capital improvements made after the original purchase. An investor who bought a property in 2015 but completed $500,000 in renovations in 2022 may still be eligible for a cost segregation study on those improvements alone – even if the original acquisition is outside the lookback window. The renovation spend has its own depreciation start date.
Kiczula says he always reviews a client’s capital improvements. Even when the original purchase is too far back, significant renovation work completed in recent years can qualify for its own study. “If they did a million dollars of work in 2022, we can absolutely do a study on that,” he says.
What the Process Requires From the Investor
The process starts with two documents: the complete property address and the investor’s fixed asset schedule, also known as a depreciation schedule. The fixed asset schedule shows what has already been reported to the IRS, which is necessary to calculate how much accelerated depreciation remains available.
From there, the cost segregation firm reviews the property using satellite imagery, county tax records, and any supporting documentation the investor can provide – closing statements, purchase contracts, appraisals. The deliverable typically includes a completed sample Form 3115, the 481(a) adjustment calculations, and guidance for the investor’s CPA to ensure proper reporting.
Why More Investors Are Filing Lookback Studies in 2026
Two developments are driving increased lookback activity. The first is awareness. Cost segregation has moved from a niche strategy used primarily on large commercial properties to a mainstream conversation among residential and mid-market investors. More investors know the option exists, which means more are asking whether it applies retroactively.
The second is the permanence of 100% bonus depreciation under the One Big Beautiful Bill for property placed in service after January 19, 2025. That permanence removes the urgency of a phaseout deadline but reinforces the structural incentive: every year that passes without a study is another year of depreciation that could have been accelerated and was not.
For investors sitting on properties acquired between 2017 and 2024, the math often still works. The question is whether they know the option exists – and whether they ask the right follow-up questions about capital improvements that may qualify independently.
About CostSegRx: CostSegRx is an engineering-based cost segregation firm led by Brian Kiczula, a member of the American Society of Cost Segregation Professionals. The firm works with residential and commercial real estate investors nationwide. CostSegRx provides complimentary estimates of benefit and supports investors and their CPAs through the full reporting process. Learn more at costsegrx.com or call (888) 850-4155.
Disclosure: Individuals or companies mentioned may have a commercial relationship with KeyCrew.
