🇺🇸 Made in America·100% U.S.-Based Team · 24+ Years in Cost Segregation
A commercial real estate investor named James in Phoenix called the Cost Seg America team last fall with a specific question. He had just completed a 1031 exchange. He had relinquished a $4.8 million apartment building he had owned for nine years and acquired a $6.5 million medical office building in the exchange. His CPA had told him cost segregation might still work on the new property, but the basis allocation was going to be complicated.
"Is cost segregation worth doing after a 1031 exchange?" James asked. "My CPA seems uncertain."
The answer was yes. But the reason was specific, and the math required understanding how Section 1031 and Section 168(k) interact at the basis level.
The Cost Seg America team performed the analysis on the new medical office building. The Year 1 cost segregation deduction on the new property's depreciable basis came to $1,425,000. At James's marginal federal bracket, that produced approximately $527,000 in actual federal tax savings in the year of the exchange. Combined with the gain deferral from the 1031 itself, the integrated strategy preserved several million dollars of capital and generated significant current-year cash flow.
This article walks through how 1031 exchanges and cost segregation interact. What changes between the relinquished property and the replacement property. How basis carries over. What gets reclassified on the replacement property. And the specific timing considerations that affect the math.
Section 1031 like-kind exchanges and cost segregation studies are two of the most powerful tax strategies in commercial real estate. Each is well-established. Each has been the subject of decades of legal development. Each survived the Tax Cuts and Jobs Act of 2017 (with 1031 restricted to real property only, and cost segregation continuing under MACRS) and the One Big Beautiful Bill Act of 2025 (which restored 100 percent bonus depreciation on cost segregation reclassifications).
The two strategies serve different purposes. Section 1031 defers the recognition of capital gain on the sale of investment real estate by allowing the proceeds to be reinvested in like-kind property. The tax on the gain is deferred, often indefinitely if the property is held until death (where the step-up in basis can eliminate the deferred tax entirely). Cost segregation accelerates depreciation deductions in the current and near-term tax years, reducing current income tax liability and generating immediate cash flow.
Used together, the two strategies compound. The 1031 exchange preserves the capital that would have gone to tax on the gain. The cost segregation accelerates deductions on the new property to reduce current income tax. The combined effect for a serious commercial real estate investor over a multi-decade career can be substantial.
The Cost Seg America team has been performing engineered cost segregation studies on 1031 replacement properties for more than 24 years. 16,000 studies. 125 IRS audits defended. Zero losses. $0 ever returned to the IRS. The average first-year savings across the 16,000+ completed studies is $438,511. Every study uses IRS Approaches 1 and 2. Every study is engineered, not estimated. Made in America, by Americans. The interaction between 1031 and cost segregation is one of the most common scenarios the team handles.
For a complete understanding of the 1031-plus-cost-seg interaction, the basic mechanics of Section 1031 need to be in place first.
A 1031 exchange allows a taxpayer to sell investment real estate and reinvest the proceeds in like-kind investment real estate without recognizing the capital gain at the time of sale. The gain is deferred. The basis in the new (replacement) property is generally the basis in the old (relinquished) property, adjusted for any boot received, any debt relief, and any additional cash invested.
The mechanics include several specific requirements:
The taxpayer must use a qualified intermediary to hold the sale proceeds. The taxpayer cannot receive the cash directly without breaking the exchange.
The replacement property must be identified within 45 days of the relinquished property closing. Up to three properties can be identified without restriction. More than three properties can be identified if specific value rules are met.
The replacement property must close within 180 days of the relinquished property closing.
The properties must be like-kind, which after the TCJA means both must be real property held for investment or productive use in a trade or business. Personal property exchanges no longer qualify under the TCJA reforms.
The replacement property value must equal or exceed the relinquished property value for full deferral. Any value shortfall (boot) is taxable in the exchange year.
When these requirements are met, the gain on the relinquished property is deferred. The basis carries over to the new property, adjusted by the formulas above. That carryover basis becomes the starting point for the cost segregation analysis on the replacement property.
The cost segregation study on the replacement property does what cost segregation always does: identifies components of the property that qualify for shorter MACRS class lives under the Whiteco 6-factor test. The total amount of basis available for reclassification, however, is determined by the 1031 mechanics.
The replacement property has two basis components for cost segregation purposes:
Carryover basis from the relinquished property. This is the basis that transferred from the old property to the new one through the 1031 exchange. It includes any depreciation already taken on the relinquished property, which remains in the basis but is now subject to the new property's depreciation schedule.
Excess basis from new equity or debt. This is any additional investment in the replacement property beyond what carried over from the relinquished property. If the replacement property cost more than the relinquished property, the excess (whether funded by cash, new financing, or other sources) is treated as new basis for depreciation purposes.
The cost segregation study can analyze the entire depreciable basis (both carryover and excess), but the treatment of each portion differs in important ways.
The carryover basis portion continues under the depreciation schedule established by the relinquished property's history. In practical terms, the property classification analysis from the relinquished property (if one was performed) continues to apply to the carryover basis. If the relinquished property never had a cost segregation study, the carryover basis is depreciating on a 39-year (or 27.5-year) schedule when it transfers to the new property. A current cost segregation study on the replacement property can apply to this basis, but the catch-up for prior years follows the Form 3115 method change rules.
The excess basis portion is treated as newly placed in service. This is the portion that gets the full benefit of current-year bonus depreciation under OBBBA's 100 percent rules. A cost segregation study on the replacement property can reclassify components of the excess basis into 5-year and 15-year MACRS classes, and the reclassified portions qualify for 100 percent bonus depreciation in the year of the exchange.
For James's $6.5 million medical office building acquired through a 1031 exchange from a $4.8 million apartment building with carryover basis of $2.1 million (after accumulated depreciation on the relinquished property), the math worked like this: The carryover basis of $2.1 million continued depreciation under the schedule that applied to it before the exchange. The excess basis of approximately $4.4 million (the difference between the new property cost and the carryover basis) was treated as newly placed in service. A cost segregation study on the excess basis reclassified roughly 32 percent into shorter MACRS classes, producing approximately $1,425,000 of Year 1 deduction under 100 percent bonus depreciation.
Property owners planning a 1031 exchange should think about cost segregation before the exchange happens, not just after. Several pre-exchange decisions affect the math on both sides of the transaction.
Cost segregation on the relinquished property before sale. Some owners do a cost segregation study on the property they intend to relinquish, well before the exchange. The Year 1 deduction from the catch-up reduces current tax. The accelerated depreciation is then partly recaptured in the exchange (or deferred along with the gain, depending on the structure), but the time value of money on the deductions taken before the exchange typically favors doing the study.
This works particularly well for properties owned for several years that never had a cost segregation study. The Form 3115 catch-up produces a large Year 1 deduction in the year before the exchange, reducing current income tax. The accelerated depreciation reduces the eventual basis in the relinquished property, which means more gain is deferred through the 1031 (since the gain is calculated against the lower remaining basis).
Property selection during the 45-day identification window. Properties identified for 1031 replacement should be evaluated for their cost segregation potential as part of the analysis. Two properties of similar purchase price may produce dramatically different Year 1 deductions through cost segregation depending on the asset class. Commercial office, medical office, retail, hotels, self storage, and similar properties typically reclassify 20 to 35 percent of purchase price. Manufacturing facilities and cold storage can reclassify 35 percent or more. A property with stronger cost segregation potential delivers more total tax benefit when combined with the 1031 deferral.
Timing the closing date relative to OBBBA. Properties placed in service after January 19, 2025 qualify for 100 percent bonus depreciation under the OBBBA. Properties placed in service before that date fall under the prior phase-down rules. A property acquired through a 1031 exchange where the closing falls after January 19, 2025 benefits from the full bonus restoration.
If you are in the middle of a 1031 exchange, the cost segregation analysis on your replacement property should be part of your tax planning. The excess basis portion of the new property qualifies for 100 percent bonus depreciation under OBBBA. The carryover basis portion can benefit from a Form 3115 lookback if the previous property never had a cost segregation study. The combined effect of the gain deferral on the exchange plus the accelerated deductions on the replacement property is typically substantial.
If you are planning a 1031 exchange in the next 6 to 24 months, consider cost segregation on the relinquished property before the exchange happens. The current-year deduction reduces your current tax, the lower basis means more gain is deferred through the exchange, and the time value of money on the accelerated deductions typically favors the strategy.
The Cost Seg America team has performed engineered cost segregation studies in coordination with 1031 exchanges across 24 years and 16,000+ properties. 125 IRS audits defended. Zero losses. $0 ever returned to the IRS. The average first-year savings across those studies is $438,511. Every study tracks basis correctly across 1031 history. Every classification documented to the IRS Audit Technique Guide standard. Engineered, not estimated. Made in America, by Americans.
The next step on your specific situation takes 30 seconds. Send the property address, the approximate purchase price, and a brief note indicating that the property is part of a 1031 exchange (including the relinquished property if relevant). The team sends back a free preliminary proposal within 24 hours.
Email: info@costsegamerica.com
Phone: 1-888-365-5023
Online: costsegamerica.com/free-proposal
Use the calculator, see your number, and request your free, no-cost proposal - delivered in 24 hours, with your flat fee quoted upfront and no obligation.