Cost segregation results depend heavily on the provider you choose. Reclassification is measured as a share of a building's depreciable basis and varies by asset class: roughly 27–38% for single-family rentals, 28–41% for office buildings, 25–39% for industrial properties, and 29–46% for hotels (see our benchmarks by property type). Within those ranges, the amount two firms capture on the same property can differ materially based on their rigor and methodology.

On a mid-sized commercial building, that difference can mean tens of thousands of dollars in first-year deductions.

Choosing the right provider matters as much as the decision to pursue cost segregation. This article shows you how to evaluate proposals, recognize warning signs, and select a provider whose work can be supported if the IRS examines it.

With the return of 100% bonus depreciation made permanent under the One Big Beautiful Bill, eligible accelerated depreciation can now be deducted in full in the first year. One important condition applies: 100% bonus is available for qualifying property acquired and placed in service after January 19, 2025, per IRS guidance on the OBBBA. Property acquired on or before January 19, 2025, including property under a written binding contract dated before January 20, 2025, stays on the prior phase-down: 40% if placed in service in 2025 and 20% in 2026. Because of this, provider selection has a direct effect on your first-year tax position.

What a Cost Segregation Proposal Should Include

A quality proposal demonstrates thorough preparation. Before signing, confirm that yours includes these components:

• Scope of work: A clear description of what the study covers
• Methodology: An explanation of the engineering approach used
• Estimated accelerated depreciation: Projected dollar amounts by asset class
• Fee structure: Transparent pricing with no hidden costs
• Timeline: Realistic delivery estimates
• Deliverables: A description of the final report and supporting documentation

The methodology section deserves close attention. Engineering-based studies follow the standards described in the IRS Cost Segregation Audit Techniques Guide (ATG), which treats a detailed engineering analysis built from actual cost records as the most reliable approach. These studies are generally easier to support than desktop estimates or rule-of-thumb calculations.

Example: A $2.5 million multifamily proposal should break down estimated 5-year and 15-year asset classifications. A single lump-sum figure, with no asset-class detail, signals incomplete analysis.

Missing components often point to a provider taking shortcuts. A proposal with no audit-support terms, for example, leaves open what happens if the IRS asks questions about the study.

The Five Questions Every Investor Should Ask

These questions help separate quality providers from firms that deliver weaker results.

1. What methodology do you use, and is it engineering-based?

The IRS ATG favors a detailed engineering analysis based on actual cost records, which it identifies as the most reliable methodology. Quality firms can explain exactly how they classify assets and determine costs. Providers who can't describe their methodology clearly may be relying on template-based shortcuts.

2. How is the property inspected, and who reviews the work?

Ask whether the inspection is in person or virtual, and what it captures, such as photos, video, measurements, and satellite imagery. Ask what credentials the engineers who review the study hold and what experience they have with your property type. A firm should be able to explain how the inspection feeds the classifications.

3. What percentage of my property's cost basis do you typically reclassify?

Reclassification is a share of depreciable basis and varies by asset class. Industrial properties typically benchmark at 25–39%, office buildings at 28–41%, and hotels at 29–46%. A firm should be able to explain the range for a property like yours. Claims well above the range may reflect positions that are hard to support on review, while unusually low results can indicate a lack of thoroughness.

4. How do you handle IRS audits or challenges?

Ask whether audit support is included in the fee and what it covers, such as written responses to IRS inquiries and support during an examination. Get the answer in writing as part of the proposal.

5. Can you provide references from similar property types?

A firm experienced with hotels should have hotel references. Medical office specialists should have medical office clients willing to speak with you. Hesitation on references can signal limited experience.

Do I really need a site visit, or can the study be done from blueprints alone?

Desktop studies exist, but the IRS ATG describes a site visit as part of a quality study, used to document physical details, construction materials, and asset conditions. The IRS does not strictly require an in-person visit. For complex or higher-value properties, engineering-based studies that include an inspection are generally easier to support. When a live visit isn't practical, a detailed engineer-guided video walkthrough can capture the same documentation efficiently.

Red Flags That Should Prompt Caution

Not every provider delivers quality work. Watch for these warning signs:

• Guaranteed dollar amounts before reviewing your property. No credible firm can promise specific results without analyzing the property first.
• No mention of IRS compliance or audit support. This leaves open how the firm would respond if the study is examined.
• A low fee with no explanation of method or engineer review. A lower fee can reflect an efficient, modeled approach. What matters is whether the firm explains how its numbers are produced and whether an engineer reviews them.
• Unwillingness to explain methodology or provide sample reports. Transparency reflects confidence in the process.
• Pressure tactics or "limited-time" pricing. Quality firms rarely need high-pressure sales techniques.
• No discussion of land value allocation. Land is non-depreciable, so a firm that ignores it may overstate results.

The lowest-priced proposal is not always the best value. Poor-quality studies can miss significant depreciation or create audit exposure. Fees also vary by property size, type, and complexity, so compare the work behind the number rather than the number alone.

Hypothetical example: An investor chose a $1,500 template-based study with no engineer review for a $4 million retail property, and that study identified $320,000 in accelerated depreciation. A second opinion from an engineering-based firm found $890,000 in qualifying assets. The $570,000 difference represents roughly $210,900 in additional first-year tax savings at a 37% marginal rate ($570,000 × 37% = $210,900), assuming the investor can currently use the deduction (see the passive activity rules below).

How to Compare Multiple Proposals Side-by-Side

Evaluating proposals calls for consistent criteria. Use this framework when comparing two or three vendors:

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Fee alone is the wrong basis for comparison. Calculate your net benefit: estimated tax savings minus the study fee.

In this example, Vendor B's $1,500 fee looks attractive. But the $260,000 gap in identified depreciation between Vendor B and Vendor A works out to roughly $96,200 in tax savings at a 37% rate ($260,000 × 37% = $96,200), if the deduction is usable. That gap is far larger than the difference in fees.

Is it worth getting multiple proposals, or should I just go with whoever my CPA recommends?

Your CPA's recommendation is a solid starting point, since CPAs often have experience with specific firms and can vouch for report quality. Even so, getting two or three proposals helps you benchmark pricing, methodology, and estimated results. Reviewing additional proposals can reveal meaningful differences in expected outcomes.

Understanding Fee Structures and ROI

Cost segregation fees typically follow three models:

• Flat fee: A set price based on property type and size
• Percentage of tax savings: A fee calculated as a portion of the first-year benefit
• Hybrid: A base fee plus a performance component

Flat fees provide cost certainty. Percentage-based fees align the provider's incentives with your outcome but can cost more on properties with strong acceleration potential. One caution: contingency arrangements can create an incentive to overstate personal property, which is why many CPAs prefer flat-fee engagements.

What matters most is the net benefit rather than the sticker price.

Example: Consider a $3.2 million industrial warehouse with a depreciable basis of $2.72 million ($3.2M purchase price minus a $480,000 land allocation), acquired and placed in service after January 19, 2025 and therefore eligible for 100% bonus depreciation. The example uses 25%, the low end of the industrial range.

• Study fee: $5,000
• Accelerated depreciation identified: $680,000 (25% of basis)
• Bonus depreciation rate: 100%
• First-year deduction: $680,000
• Tax savings at a 37% marginal rate: $251,600 ($680,000 × 37%)
• Fee multiple: roughly 50x

In this example, a $5,000 fee produces $251,600 in year-one tax savings, assuming the investor can use the deduction currently. Evaluate every proposal on net return rather than fee alone.

What if I already did a cost segregation study years ago? Can I get another one done?

Yes. If your original study was low-quality, or you've made significant improvements to the property, a "look-back" study can capture missed depreciation. You can file Form 3115 to change your accounting method and claim overlooked deductions through a Section 481(a) catch-up adjustment, without amending prior returns. This route generally applies once a property has been reported on two or more filed returns; if only one return has been filed, an amended return may be the better fit, so confirm the timing with your CPA. Related: cost segregation study timing.

Who Can Actually Use the Deductions

Accelerated depreciation only helps if you can use the resulting loss. Under the passive activity rules in IRC §469, rental real estate is generally treated as a passive activity, and passive losses can normally offset only passive income. Losses you can't use are suspended and carried forward to future years, and they are generally released in full when you dispose of your entire interest in a fully taxable transaction, per IRS Publication 925.

Several paths let investors use these losses against other income:

• The $25,000 special allowance. Taxpayers who actively participate in a rental may deduct up to $25,000 of losses against nonpassive income. This allowance phases out between $100,000 and $150,000 of modified adjusted gross income, as described in Publication 925.
• Real estate professional status. Under IRC §469(c)(7), a taxpayer who spends more than 750 hours and more than half of their working time in real property trades or businesses in which they materially participate can overcome the presumption that rentals are passive. The taxpayer must then also materially participate in the rental activity, or elect under Reg. sec. 1.469-9(g) to treat all rental real estate as a single activity, for the losses to be nonpassive.
• The short-term rental approach. When a rental's average guest stay is seven days or less, it is not treated as a "rental activity" under the passive activity regulations. If the owner also materially participates, the losses can be nonpassive. A short average stay alone is not enough; material participation is still required.

Nonpassive losses are still subject to the excess business loss limit under Section 461(l), which caps the net business loss you can deduct against other income in a year. The excess carries forward as a net operating loss.

Before commissioning a study, confirm with your CPA how you expect to use the deduction. That determines whether the first-year benefit is immediate or deferred.

What Happens at Sale: Depreciation Recapture

Cost segregation accelerates deductions, but it also affects your tax picture when you sell. Under IRS Publication 544, gain attributed to prior depreciation is subject to recapture:

• Section 1245 property (the 5- and 7-year personal property a study identifies) is recaptured as ordinary income to the extent of depreciation taken.
• Section 1250 property (the building and 15-year land improvements) is recaptured as ordinary income only to the extent depreciation exceeded straight line, which bonus depreciation causes on 15-year assets. The straight-line portion is unrecaptured Section 1250 gain, taxed at a maximum 25% rate.

Because accelerating deductions into shorter-life assets can increase the ordinary-income portion of recapture at sale, cost segregation shifts the timing and character of tax rather than eliminating it. Many investors manage this by holding the property, planning the sale year, or using a 1031 exchange to defer some or all of the gain. Exchanges cover real property only, and Section 1245 recapture can still apply. Model the exit with your CPA so the up-front benefit still makes sense over your expected hold.

After You Choose: What to Expect Next

Once you've selected a provider, the process moves quickly.

Typical timeline: R.E. Cost Seg delivers Rapid Reports in 5 business days and fully engineered studies in 15–20 business days, after all requested information is received. Other firms' timelines vary with property complexity and inspection scheduling.

Information you'll provide:

• Closing statement or purchase documentation
• Property details (square footage, year built, construction type)
• Any renovation or improvement records
• For Fully Engineered Studies, access for a site visit or virtual walkthrough

What you'll receive:

• A detailed asset classification report
• Depreciation schedules by asset class
• Supporting documentation for your CPA
• A fixed asset schedule in spreadsheet format

Your cost segregation report gives your CPA what's needed for the return. Quality providers coordinate with your CPA to support a smooth filing.

If the property has already been reported on two or more filed returns, your CPA will file IRS Form 3115 to implement the study results through a Section 481(a) adjustment.

Key Takeaways

• A quality proposal clearly outlines methodology, estimated reclassification, fees, and audit support. Missing components signal incomplete preparation.
• Ask the five questions. Vague or defensive answers are warning signs.
• Compare at least two or three proposals using consistent criteria. Focus on net benefit rather than price.
• Confirm who can use the deduction before you commit. Passive activity rules, real estate professional status, the short-term rental approach, and the excess business loss limit determine whether the first-year benefit is immediate or deferred.
• Plan for recapture at sale. Cost segregation shifts the timing and character of tax, so model your exit with your CPA.
• Engineering-based methodology and audit support matter most on complex or higher-value properties.

Choosing a cost segregation provider carefully helps you capture the depreciation available under current law and support it if examined. With permanent 100% bonus depreciation in effect for qualifying property, eligible accelerated depreciation can be deducted in the first year, if you can use the loss.

See how much accelerated depreciation your property may contain. Request your free proposal to get an engineering-based study with IRS audit support included.