Cost Segregation Study: How It Works and When It's Worth It

By CostSegregationMatch · Tax rules and prices checked October 7, 2026 · How we make money

A cost segregation study is a report that splits the cost of a rental or business building into parts. Some of those parts can be written off on your taxes much faster than the building itself.

Residential rental buildings generally use a 27.5-year write-off period; most other business buildings use 39 years. A study identifies parts like appliances, carpet, fences and parking areas that may qualify for 5, 7 or 15 years instead. Eligible faster parts acquired and placed in service after January 19, 2025, generally qualify for a full first-year write-off under bonus depreciation, unless an election or exclusion applies. (IRS Publication 946)

A study does not create more cost to deduct. It moves allowable deductions into the early years. In the worked example below, a $500,000 rental goes from about $6,700 of first-year depreciation under a building-only schedule to about $93,200.

Is it worth paying for? That comes down to three things: whether you can use the extra deduction now, whether the value of getting the tax benefit early is bigger than the full cost, and how long you'll keep the property. If rental-loss limits apply, you may not be able to use the extra deduction against your paycheck right away. Check that before you buy.

Jump to: The worked example · Is it worth it? · Check your own numbers · How to get one

Already know you want a study? You can compare three published offers by price, property limits, and how much of the work you do. No account, email, or phone number needed.

Find My Cost Seg Provider

What is a cost segregation study?

When you buy a building, you pay one price. But for taxes, you didn't buy one thing. You bought land, a building, a driveway, a fridge, carpet, and more. Each kind of thing has its own write-off period. (Writing off a cost a little each year is called depreciation.)

A cost segregation study sorts your one price into those piles and puts a dollar amount on each pile.

The IRS describes it the same way. When you only have one lump-sum cost, cost estimating is used to "segregate" or "allocate" that cost to individual assets. The IRS calls this a cost segregation study, a cost segregation analysis, or a cost allocation study. They all mean the same work. (IRS Publication 5653, chapter 1)

The four piles

These are the usual recovery periods under the general depreciation system. Special asset rules and the alternative depreciation system can change them.

Sources: IRS Publication 527, Table 2-1, IRS Publication 946, and IRS Publication 5653, chapter 2.

Not every item is clear-cut. A study may also treat things like wall coverings, some lighting, or wiring that serves special equipment as personal property. The IRS says items like these may or may not qualify. It depends on the facts of your building. That gray area is why the paperwork behind a study matters.

Is it legal?

Yes. The rules come from the normal depreciation system in the tax code. In a 1997 Tax Court case, Hospital Corporation of America v. Commissioner, the court held that personal property inside a building can be depreciated as personal property. The IRS accepted that part of the ruling. It also publishes a guide its agents use to review these studies. (IRS Publication 5653, chapter 2)

Who does what

A provider makes the study. Your tax preparer uses it on your tax return. The study is not the tax return, and a free estimate is not the finished study.

How cost segregation works: one property, step by step

The work has five main parts.

1. Find the starting number. For a normal purchase, that's what you paid, plus costs that get added to it, minus the land. This is your depreciable cost.
2. Find the parts. The provider uses documents, a questionnaire, photos, or an inspection.
3. Price each part and put it in the right pile.
4. Check the math. The allocations have to reconcile to the relevant cost basis, with land kept separate.
5. Hand it to your tax preparer. They put the new numbers on your return.

The example

This property is made up. It is not a client result, and the numbers are not typical or promised.

• A residential rental, bought and ready to rent in July 2026.
• Price: $500,000. Land: $100,000. Depreciable cost: $400,000.
• We assume a study moves $60,000 (15%) to 5-year property and $28,000 (7%) to 15-year property. The other $312,000 stays as building.
• All $88,000 of faster parts qualify for 100% bonus, with no election out. The building uses the 27.5-year general depreciation system and the mid-month rule. We assume no later sale, improvements, or change in use when comparing the full schedules.

The comparison starts with all $400,000 on the building schedule. That is an illustration, not a rule that every owner without a study must follow. Costs already correctly assigned to separate assets would change the comparison.

That 22% is our assumption. One provider, R.E. Cost Seg, says on its site that single-family rentals typically land at 20% to 30%. That is the company's claim. Your study sets your real number.

Here is the math.

• Building-only example: $400,000 ÷ 27.5 years = about $14,545 a year. The first year only counts 5.5 months (mid-July through December), so $400,000 ÷ 27.5 × 5.5 ÷ 12 = $6,667, rounded. Tax rules call this the mid-month rule.
• With the study: all $88,000 of faster parts in year one, plus the building: $312,000 ÷ 27.5 × 5.5 ÷ 12 = $5,200. Total: $93,200.

You get $86,533 more in year one. You get $3,200 less in each remaining full recovery year. The total is $400,000 either way. The final partial year also has a smaller deduction. We calculate with unrounded numbers, then round the figures shown here to the nearest dollar. (IRS Publication 527, depreciation methods and conventions)

That is the whole idea. A study changes timing, not the total.

Bonus depreciation in 2026: the dates that decide your first year

Cost segregation and bonus depreciation are two different things. The study finds the faster parts. Bonus depreciation is a separate rule that lets you write off those faster parts in the first year instead of over 5, 7 or 15 years.

How much bonus you get depends on when you acquired the property and when it was ready and available to rent or use—its placed-in-service date.

These are the general rates for otherwise eligible property, assuming no election out or other special election. Property required to use the alternative depreciation system and some used-property acquisitions do not qualify. The table does not cover special timing rules for aircraft or certain property with a long production period.

Sources: IRS Publication 946 (2025), IRS Notice 2026-11, and IRS Revenue Procedure 2026-15, section 2.01 for the earlier phase-down and 20% rate.

Four things to know:

• "Bought" is a tax term. If you signed a binding contract before the cutoff and closed after it, the contract date can be the one that counts. Ask your tax preparer.
• "Ready to use" is not the day you order the study. A study done today does not change the dates on a property you bought years ago.
• Bonus only covers the faster parts. It doesn't cover land. For ordinary rentals and commercial buildings, it doesn't cover the main building either.
• A study can still accelerate deductions without bonus. In our example with no bonus at all, first-year depreciation would be $18,600 instead of $6,667. With 20% bonus it would be $33,520. These two alternatives assume the usual half-year convention for the faster parts; the mid-quarter rule or a different depreciation method would change them.

You can also elect not to take bonus, generally by property class. Some owners do that to spread deductions out. There is also a special 40% election for otherwise eligible property in the first tax year ending after January 19, 2025. That's a call for you and your tax preparer; an election already made can affect a later study.

Is a cost segregation study worth it?

A study is more promising when three things are true. You can use the extra deduction soon. The value of getting the tax benefit early comfortably exceeds the full cost. And the result still works with your plans to sell.

The first one can trip you up. Here is the same property and the same study with three different owners. For the fees, we assume $3,000 in total: $2,500 for the study and $500 of extra tax-prep time. Those are round numbers we made up for the example.

For this table, assume the rental breaks even before depreciation, no other losses use up the limits, and no basis, at-risk or other restriction changes the result. The middle owner qualifies for the full $25,000 rental-loss allowance and is not married filing separately. These are one-rate federal examples: they leave out state differences, changes across tax brackets, and any tax treatment of the fees.

Same building. Same study. Same $86,533 on paper. Three very different results.

The third owner's disallowed passive loss carries forward. But they paid $3,000 this year for a benefit they cannot use yet; its later use depends on their income and what happens to the activity.

In the middle row, up to $25,000 of rental loss can be used. Without a study, this owner's $6,667 loss was already usable. So the study adds $25,000 − $6,667 = $18,333 of usable deduction this year. The rest waits.

Why the same study gives three results

Rental activities are generally "passive" by default. Unless an exception applies, a passive loss can offset passive income, like qualifying profit from other rentals, but cannot lower the tax on your paycheck. (IRS Publication 925)

If the passive-loss rules stop you from using a loss this year, it carries forward. You may use it against later passive income or an available special allowance. Remaining losses are generally released when you dispose of your entire interest in the activity to an unrelated buyer in a fully taxable transaction. Selling one property is not always the same as disposing of an entire activity.

There are four common ways the extra deduction becomes usable now:

1. You have passive income. Profit from other rentals that counts as passive income can soak it up. Ordinary investment interest, dividends and stock-sale gains generally cannot.
2. You're a real estate professional. More than half the personal services you perform in all trades or businesses, and more than 750 hours a year, must be in real property trades or businesses in which you materially participate. You also have to materially participate in the rental activity. These are separate tests; a job title alone is not enough.
3. It's a short-term rental you run yourself. If the average guest stay is 7 days or less, the IRS does not treat it as a rental activity under these rules. If you also materially participate, the loss is not passive.
4. The $25,000 allowance. Eligible individuals who actively participate in rental real estate can use up to $25,000 of rental loss against other income. You generally need at least a 10% ownership interest, counting your spouse's interest too. The allowance shrinks by $1 for each $2 of modified adjusted gross income above $100,000 and is generally gone at $150,000. Married filing separately has different limits: at most $12,500 if you lived apart all year, phasing out from $50,000 to $75,000; no allowance if you lived together at any time.

Other limits can apply too, including basis, at-risk and excess-business-loss limits, and personal use of a vacation home. Your tax preparer is the one who can tell you where you stand. If you don't have one, the IRS has a plain guide to choosing a tax professional.

Five checks before you pay

A quick first-year fee check: divide the full cost by your assumed tax rate on the extra deduction. With $3,000 in fees and a 32% rate, $3,000 ÷ 0.32 = $9,375. That's how much extra usable deduction you need for the first-year tax reduction to cover the fees. In this July example, with $400,000 of depreciable cost, 100% bonus and full use, that's about 2.4% of the cost moving to the faster piles. This checks first-year cash flow, not the value over the whole holding period.

A later study may still let you catch up. If the answer today is "not yet," ask your preparer about timing before you postpone. Filing deadlines, earlier elections and the method-change rules can affect the route. See studies for property you already own.

What the first-year number is really worth

The owner in the top row pays $27,691 less tax in year one. Then they pay $1,024 more in each of the 27 remaining full recovery years ($3,200 × 32%), plus about $43 more in the final partial year, because their deduction is smaller. Add up every year using the unrounded figures and the tax difference comes to zero.

So the win is getting the money early. How much is that worth? At a 5% annual discount rate, the timing benefit is worth about $12,100 in today's dollars. This assumes the same 32% rate on every deduction, full use as deductions arise, tax savings and later tax costs at each model year-end, and no sale or change in use through the full recovery period. The first tax saving is modeled one year after the upfront fees.

That is still about four times the $3,000 cost. But the gross timing benefit is $12,100, not $27,691. After $3,000 in fees paid upfront, the net value is about $9,100. Compare that timing value to the fee, and model your own sale plans separately.

Check your own numbers

Use this with a provider's estimate, or try a what-if with your own guess. It works in your browser. The tool itself does not send or save your entries. The copy button puts your summary on your clipboard for you to share.

Press "Load the example" to see the property above. The result should match this page: $86,533 extra, a $27,691 tax cut at 32%, $24,691 after $3,000 in fees, and $9,375 needed to cover the fees.

If the numbers look good, the next step is to see which kind of study fits your property.

Find My Cost Seg Provider

If you still don't know how much of the deduction you can use, take the questions for your tax preparer with you first.

How much does a cost segregation study cost?

It depends on the property and on how much of the work the provider does. Here are three published offers from two companies. They are three different levels of help, not three quotes for the same job.

Prices come from the providers' own pages: CostSegregation.com, Rapid Report, and Fully Engineered Study. Checked October 7, 2026. They are examples and starting prices, not quotes for your property. We have not bought these studies. These provider links are unpaid. How we make money.

For bigger or more complex buildings, providers quote one at a time. KBKG says properties over $1.5 million of tax basis get a custom quote. R.E. Cost Seg says engineering-based studies across the industry typically run $3,000 to $15,000 or more. That is the company's own statement, not our data.

Add the tax work before you compare

Full cost = study fee + extra tax-prep work + any extras you need.

If you already owned the property in an earlier year, you may need an extra tax form, Form 3115. R.E. Cost Seg publishes Form 3115 preparation as a $600 add-on for both its Rapid Report and Fully Engineered Study. Your own tax preparer may charge for extra time too. Ask who prepares the form, who files it, and for the combined fee so you don't count the same work twice. An unknown fee is not a $0 fee.

Find My Cost Seg Provider

What a good cost segregation study includes

The IRS guide says a quality study is one that is accurate and well documented. A long PDF or a big deduction number does not prove either one. (IRS Publication 5653, chapter 4)

Whatever kind of study you buy, you should be able to find these in the report:

1. Who prepared it and what their experience is.
2. How they did it, step by step.
3. What records they used: closing statement, appraisal, plans, invoices, photos.
4. How the land value was set. Land comes out first.
5. A list of each faster item with its cost.
6. The reason each of those items qualifies.
7. A check that the parts add up to the tax cost being allocated.
8. Schedules your tax preparer can review and use.

Does the IRS require an engineer or a site visit?

The IRS guide does not prescribe a preparer credential or one required method. It does describe site visits as part of a quality study. Here is what it says.

• The IRS has not set required standards or a required method for these studies.
• The guide says there are no prescribed preparer qualifications. It generally favors engineering and construction knowledge, and recommends qualified appraisers for acquired or used properties.
• The guide says a quality study includes a site visit, and that a field inspection is recommended. It matters most when there are no building plans.
• The guide favors studies built on real cost records or careful cost estimates as more reliable. A study that just applies a rule-of-thumb percentage with little documentation should be viewed with caution.

Ask how the provider will verify your property's assets and values. Have your tax preparer review whether the proposed records and inspection work are enough for your building.

One more thing. The IRS guide is written for its own examiners. It says it is not official legal authority. It is still the best public picture of what the IRS looks for.

Will a study get me audited?

We don't have a reliable study-specific audit rate to report, so we won't guess. What we can say: the IRS has a guide of more than 300 pages for reviewing them, it added a section on residential rentals in its 2024 update, and it says the line between building and personal property is often argued over. Good documents are what you would show if asked. (IRS Publication 5653, preface and chapter 2)

Ask what "audit support" covers

Check the scope behind the phrase. R.E. Cost Seg's published support covers written answers about its own study. It does not cover representing you before the IRS, testifying, or preparing or amending your tax return.

Ask every provider: "If the IRS questions this study, what will you do at no extra charge, and what is left for my tax preparer?"

Our methodology page explains how we compare these points across providers.

How to get a cost segregation study

1. Ask your tax preparer two questions. "Would faster deductions help me this year?" and "What does the study need to include for you to use it?"
2. Gather your records. See the list below.
3. Pick the kind of study that fits. Check each provider's limits on cost, number of units, and renovations.
4. Get the price and scope in writing. Some products show a price at checkout; a full-service study may start with a proposal. Ask what's included, what's extra, and who prepares Form 3115 if you need it.
5. Do your part. Fill in the questionnaire, send the documents, or do the video walk-through.
6. Give the report to your tax preparer. They put it on your return and keep a copy with your records. You should keep one too.

Records to gather

• Closing statement and purchase agreement, or your construction cost records
• The land value you used, or plan to use, on your tax return
• Your current depreciation schedule, if you've filed for this property before
• The date you bought it and the date it was ready to rent or use
• Invoices for renovations and improvements
• An appraisal, floor plans, and photos, if you have them
• Any plans to sell or change how you use the property

Each provider will tell you what it needs. This list just saves you a second trip to the filing cabinet.

How long does it take?

Here is what one provider publishes. R.E. Cost Seg says its Rapid Report usually takes about 5 business days after you pay and finish the questionnaire. It says its Fully Engineered Study typically takes 15 to 20 business days after it has your documents and the virtual inspection is done. (R.E. Cost Seg services, checked October 7, 2026.)

Software depends on how fast you enter your information. Other providers may be faster or slower.

When should you order?

Try to finish the study before filing the return that will use it. If the return is already filed, ask your preparer promptly which correction or accounting-method-change route is available and what deadlines apply. Read the next section.

Our comparison page has a provider-question brief you can copy and use for a proposal request or provider call.

Find My Cost Seg Provider

Already own the property? You can still do a study

Yes. You can order a study years after you bought the property. This is often called a look-back study.

For an eligible change in accounting method, your tax preparer can use Form 3115 rather than amend each old return. The form changes the depreciation method and reconciles the earlier deductions. A favorable catch-up—a negative section 481(a) adjustment—is generally deducted in the year of change, subject to the same loss limits. Other situations can require an amended return or a different procedure. Have your preparer confirm which route applies. (IRS Publication 946, "Changing Your Accounting Method"; Revenue Procedure 2015-13, section 7.03)

For tax preparers: an eligible change from an impermissible to a permissible depreciation method can use Revenue Procedure 2025-23, section 6.01, designated change number 7. Eligibility and filing requirements still apply.

A look-back example

Take the same $500,000 rental. This time it was bought and ready to rent in July 2022. The owner gets a study in 2026.

Assume the owner used the building-only schedule on the earlier returns, still owns the property, qualifies for the method change, and all $88,000 of faster property qualified for 100% bonus with no election out.

At a 32% tax rate, $73,733 is $23,595 less tax in 2026, if the owner can use it all. The same loss limits apply here as anywhere else.

Two things to know:

• Your bonus rate comes from your old dates. This example's eligible property was acquired and placed in service in July 2022, when the general rate was 100%. Otherwise eligible property acquired after September 27, 2017, and placed in service in 2024 generally had a 60% rate. Elections and special rules can change the result.
• The study provider may not prepare Form 3115. Software can give you the catch-up number without preparing or filing the form. Ask who does it and what it costs.

What happens when you sell the property?

Faster deductions now can mean more tax when you sell. You don't automatically pay it all back. But the sale is part of the deal and belongs in the comparison.

Three things change:

• You have fewer deductions left. What you wrote off early can't be written off again.
• Part of your gain can be taxed at your regular rate. When you sell section 1245 personal property for a gain, the gain is generally ordinary income up to the depreciation allowed or allowable on it. This is called depreciation recapture. (IRS Publication 544)
• The building is treated differently. For individuals, gain tied to normal building depreciation—called unrecaptured section 1250 gain—generally has a maximum federal rate of 25%. Other recapture rules, state taxes and the net investment income tax can also matter. (IRS Topic 409; IRS Publication 544)

A small example of the personal property rule. Say you fully wrote off $10,000 of carpet and appliances, leaving $0 of adjusted tax basis. Years later, a supported allocation gives those items $3,000 of net sale proceeds. The gain is $3,000 minus $0, so the ordinary-income recapture is $3,000, not $10,000. The allocation needs evidence; you cannot just pick a low value to reduce the tax.

In a real sale, the price has to be split among the land, the building, and the other parts. That split is work for your tax preparer.

Ask them this before you order: "If I sell in the year I expect to, how does my tax compare with and without the study?"

A short hold makes that question more important. There is no magic number of years. It depends on your tax rates now and later.

Who a study fits, and who should wait

Questions to ask your tax preparer before you pay

Copy these into an email or bring them to your next meeting.

More questions about cost segregation studies

Can I do a cost segregation study myself?

The IRS guide does not prescribe a preparer credential. The hard part is the proof. You need to show what each item is, why it qualifies, and what it cost, and it all has to reconcile to the tax cost being allocated. Self-guided software exists for smaller properties that fit its limits. Check with your tax preparer that its report gives them what they need.

Does my CPA do the study?

Ask whether your CPA prepares studies or uses a specialist provider. Some accounting firms have their own study teams. The study and the tax-return work are separate jobs, even when the same firm does both.

Is there a minimum property value?

No rule sets one. You'll see cutoffs like $300,000 or $750,000 online. Those are rules of thumb or one company's limits. Start with the math: your extra usable deduction, times your tax rate, against the full cost. Then compare the value of getting that deduction early and the tax effect of your expected sale.

Is it based on my down payment or what the property is worth today?

Neither. It's based on your tax basis. For a normal purchase, that's what you paid, including the part you borrowed, plus certain closing costs. (IRS Publication 946) A refinance does not by itself reset the property's depreciable basis. New improvements paid for with the proceeds can add separate depreciable cost.

Do I need an LLC?

No. An LLC is not what makes a cost depreciable. What matters is that you have depreciable cost in property used for business or to earn income. That can include improvements you pay for in a space you lease.

Do I need a study to take bonus depreciation?

Not always. Things you buy on their own, like furniture for a rental, already have their own cost and can qualify without a study. A study is for the parts buried inside the price of a building.

Is cost segregation the same as Section 179?

No. Section 179 is a separate rule with its own limits. The maximum is $2,560,000 for tax years starting in 2026, reduced dollar for dollar when qualifying property placed in service exceeds $4,090,000. A business-income limit also applies. Rental assets face leased-property restrictions, especially for noncorporate lessors. Land and land improvements do not qualify. Ask your preparer which assets qualify. (IRS Publication 946)

How often can I do a study?

One study covers what you bought. If you later renovate or add on, that is new cost. It can be studied when the work is finished and in use.

Your next step

If you can use the deduction and the math works, pick the level of help your property needs. Then confirm the full fee and what your tax preparer needs from the report.

If you're not sure you can use the deduction, start with the questions for your tax preparer. Ask when ordering would help, and what filing dates matter.

Find My Cost Seg Provider

Compare published prices, property limits, and how much work each option asks of you. No account, email, or phone number needed.

How we checked this page

Tax rules come from IRS publications, notices and accounting-method procedures. Each one is linked next to the claim it supports. Prices and service details come from each provider's own pages. We checked the sources on October 7, 2026.

The example property is made up to show the math. We have not bought or tested these studies. A provider's own description tells you what it offers, not how well it performs. This page has not been reviewed by a CPA or an engineer.

Read our methodology and editorial standards. See something wrong? Send a correction.