Short answer

A cost segregation study is worth it when the tax it defers, after the study's fee and after the recapture you will eventually pay, is large enough to matter and arrives when you can use it. That sentence contains five checks, and every one of them can be answered before you pay anyone: the size of the depreciable basis, what the property physically contains, whether you can use accelerated deductions this year under the passive activity rules, how long you will hold, and whether your state follows the federal rules. This article turns those five into a checklist you can take to your tax adviser. It does not give a dollar threshold, because the honest answer varies with the owner, not just the building. It is general education, not tax advice.

What the study changes, in one paragraph

Land is never depreciated. A residential rental building is written off over 27.5 years and a nonresidential building over 39. A study identifies the parts of the price that are not the building: 15-year land improvements and 5- or 7-year personal property. Those parts are depreciated faster and, when they qualify, expensed in the first year under bonus depreciation, which for qualified property acquired after January 19, 2025 is a permanent 100 percent. Total depreciation over the property's life does not change; its timing does. On sale, depreciation on the reclassified property is recaptured as ordinary income and the building's depreciation is taxed at up to 25 percent. Every "worth it" question is a question about that timing trade.

The five checks

CheckQuestion to answerWhere the answer comes from
1. BasisHow much depreciable basis is there after separating land?Closing statement, appraisal or assessor ratio
2. ContentsHow much of the property is land improvements and personal property rather than structure?A walk-through, the appraisal, the purchase inventory
3. Usable lossCan I use an accelerated deduction this year?Your adviser, applying the passive activity rules to your return
4. Holding periodHow long will I hold, and how will I exit?Your plans
5. StateDoes my state follow federal bonus depreciation?Your adviser

Check 1: basis

The study's benefit scales with the depreciable basis. Land is separated first, by fair market value at purchase. In a market where land is most of the price, the pool the study works on is small; in a market where the building dominates, it is large. Ask your adviser what the depreciable basis is likely to be before asking what a study would find inside it.

Check 2: contents

Two buildings with the same price can produce very different studies. Furnished units, appliances, carpeting, site paving, fencing, lighting, drainage and equipment that serves a business function are what a study reclassifies. A bare structure on a small lot with unfurnished units has little to reclassify; a furnished building with parking and grounds has a great deal. Walk the property with this in mind. The IRS guide's methods start from the actual components, and the quoted percentages in forums are averages of other buildings, not information about yours.

Check 3: usable loss

This is the check most projections skip. Rental losses are generally passive. If the accelerated deduction creates a loss, you can use it against wages or business income this year only if one of the exceptions applies: the special allowance of up to $25,000 for active participants, phased out between $100,000 and $150,000 of modified adjusted gross income, or real estate professional status with material participation. Otherwise the loss is suspended and carried forward, offsetting passive income in later years and generally released in full when you dispose of your entire interest in a fully taxable transaction. A suspended loss is not worthless, but a projection that shows a saving this year for an owner who cannot use the loss is wrong.

Check 4: holding period

The study defers tax; recapture collects part of it later at ordinary rates. The longer you hold, and the more you do with the deferred tax in the meantime, the better the trade. A sale within a few years can turn it negative once the fee is counted. Installment sales do not defer section 1245 recapture. If you are likely to sell soon, say so before commissioning a study.

Check 5: state

Many states do not follow federal bonus depreciation, or follow it with adjustments, so the state result can differ from the federal one and require a separate schedule for years. Your adviser knows your state; the practitioner may not.

A worked way to decide

  1. Ask your adviser for the depreciable basis after land and a rough view of contents.
  2. Ask the adviser whether you can use a loss this year, and how much.
  3. Ask a practitioner for a scoped estimate of what a study would likely reclassify, with the caveat that it is an estimate, and for the fee.
  4. Have the adviser model the timing benefit under your marginal rate, your state, an assumed holding period and recapture at sale, less the fee.
  5. Decide on the model, not on a percentage or a promise.

A practitioner who cannot support step 3 with a description of method, or who prices step 3 as a share of a saving nobody has modeled, is a reason to stop. Practitioners who practice before the IRS are also subject to Circular 230's restrictions on contingent fees for most return-preparation work, which your adviser can explain.

Situations where the answer is usually no

  • The loss will be suspended and you expect no passive income and no sale for years.
  • You plan to sell within a short period.
  • The property is mostly land value or a bare structure with little to reclassify.
  • The basis is small enough that the fee consumes most of the timing benefit.
  • Personal use exceeds the greater of 14 days or 10 percent of rental days, so rental deductions are already limited.

Situations where the answer is often yes

  • A furnished or amenity-heavy building with substantial site work, acquired after January 19, 2025.
  • An owner who can use the loss: a real estate professional, an active participant under the allowance, or someone with passive income to offset.
  • A long expected hold, or a disposition plan such as a like-kind exchange that your adviser has reviewed.
  • An existing building never studied, where a look-back can be applied through a change in accounting method.

None of these is a rule. They are the patterns the five checks tend to produce.

What people ask on Reddit and other forums

The "is cost segregation worth it" threads on r/realestateinvesting and r/tax, and "cost segregation reddit" searches generally, ask the same things in different words. The searches that lead people to these threads are usually phrased "cost segregation for small rental" and "when does cost segregation make sense".

"Is there a minimum property value?" Not in the law. Vendors quote thresholds because their fee is fixed and the benefit scales with basis; treat any number as a rule of thumb and run the five checks.

"I'm high income with a W-2. Everyone says do it." Check 3 decides. Unless you are a real estate professional or have passive income, the loss is suspended. That is not nothing, but it is not this year.

"Bought in 2023. Worth it now?" Possibly, through a look-back study and Form 3115. The catch-up uses the bonus rules in force when the property was placed in service, not today's 100 percent.

"Does the study pay for itself?" Only if the modeled timing benefit, at your rate and holding period, exceeds the fee plus the effect of recapture. Ask for the model, not the slogan.

Questions people also ask

Is cost segregation worth it on a $300,000 rental?

It depends on the depreciable basis after land, what the property contains, whether you can use the loss this year, how long you will hold, and your state. Run the five checks with your adviser; there is no fixed threshold.

Can a study lose me money?

Yes, if the fee exceeds the timing benefit you can actually use, or if you sell soon after and recapture arrives before the deferral has done anything.

Does 100 percent bonus depreciation make it always worth it?

No. Bonus depreciation makes the first-year deduction larger for property acquired after January 19, 2025; it does not change whether you can use the deduction or what happens at sale.

Should I ask the cost seg firm or my CPA?

Both, in that order reversed: the adviser first, because only the adviser can say what a study would do on your return.

What if I decide no?

Nothing is lost. Depreciation of the whole cost continues over 27.5 or 39 years, and a study can be applied later through a change in accounting method if circumstances change.

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