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Tax

Cost segregation

An engineering study that reclassifies parts of a building into shorter depreciation lives.

Rent & lease payments Tax

This page defines one term. If you have arrived here from a listing or a broker's summary, the useful order is: read what it is, then read what it does not tell you, and only then look at the number you were quoted. What would mislead: any single measure on a property is a summary of one year, one assumption or one document. None of them describes a whole investment, and the misreading section below is there because each of these terms has one that is extremely common.

What it is

A cost segregation study breaks a purchase price into components and assigns each to its correct asset class. Carpet, cabinetry, specialty electrical, process plumbing and similar items can be personal property with short recovery periods; sitework, paving, fencing and landscaping can be land improvements with their own class; the structure remains 39-year or 27.5-year property.

Because more of the cost lands in short-life classes, deductions are pulled forward into the early years of ownership. The total deduction over the life of the asset does not change — the timing does.

What it tells you

How much of a building's cost can legitimately be recovered faster than the default schedule, based on an engineering analysis of what was actually bought.

What it does not tell you

Whether the acceleration is worth it. The study costs money, the benefit is the time value of an earlier deduction, and reclassified components are subject to their own recapture rules on sale.

The common misreading

Treating it as extra deductions rather than earlier ones. Pulling deductions forward increases the taxable gain later and can convert part of that gain into ordinary-income recapture on the personal-property components.

Where it sits in the sequence

Every commercial deal runs the same arithmetic in the same order. This measure is one line in it.

The list below is how a whole deal is worked out, from the rent on the schedule to the cash an owner keeps. Find the step this term belongs to and you can see what it has already counted and what it has not. What would mislead: quoting one line of this sequence as though it were the answer. Each step subtracts something real, and the ones after it subtract more.

  1. Rent roll Contract rent, tenant by tenant Start from the leases, not from a summary. Each line has a start date, an expiry, an escalation schedule, options, and any free rent or unamortised concession still running. The rent roll is a legal document set, and the estoppel certificates are how a buyer confirms the tenants agree with it.
  2. Potential gross income Contract rent + market rent on vacant space + other income + expense recoveries What the property would produce fully leased, including parking, signage, storage, late fees and the reimbursements tenants owe for taxes, insurance and common-area costs. Recoveries are income and the matching expense is an expense — netting them hides the recovery ratio.
  3. Effective gross income Potential gross income − vacancy − credit loss − concessions Deduct what will not actually be collected: physical vacancy, tenants who do not pay, and concessions granted. Using an assumed market vacancy rather than the property's own history is one of the most common places a model becomes optimistic.
  4. Operating expenses Taxes + insurance + utilities + repairs + management + admin + payroll The cost of running the building for a year. Two lines deserve independent verification rather than acceptance: property taxes, which are frequently reassessed on a sale, and insurance, which is quoted to the buyer and not inherited from the seller. A market management fee belongs here even if the current owner charges none.
  5. Net operating income Effective gross income − Operating expenses = NOI The property's own income, before financing and before tax. This is the number that value, cap rate and every lender covenant are calculated from, which is exactly why it is the number most often presented flatteringly.
  6. Value and cap rate Value = NOI ÷ Cap rate · Cap rate = NOI ÷ Price One equation used in both directions. Divide NOI by a cap rate to estimate value; divide NOI by a price to see what a deal is being priced at. Because value is derived from NOI, every dollar added to or removed from NOI moves the value by a multiple of itself.
  7. Capital items below the line NOI − capital expenditure − tenant improvements − leasing commissions Excluded from NOI by convention, but paid in cash. Roofs, parking lots, HVAC replacement, fitting out space for a new tenant and the commission that won the lease all come out of the same account. A reserve for them is the difference between an honest analysis and a brochure.
  8. Debt service Cash flow before tax = NOI − annual debt service (− capital items) Interest and principal on the loan. This is where DSCR is tested, where the loan constant decides whether leverage is adding to or subtracting from cash flow, and where a covenant breach can divert income into a lender-controlled account before the owner sees it.
  9. After tax Taxable income = NOI − interest − depreciation ± other adjustments Cash flow and taxable income are different numbers. Depreciation is deducted though no cash left, principal repayment is cash out though it is not deductible, and the resulting loss may be suspended under the passive activity rules rather than used. At sale, recapture and gain settle the difference.

Primary sources

The authority on this, rather than an article about it.

The tax picture around it
In general US federal terms: rental income is ordinary income, reduced by operating expenses, mortgage interest and depreciation. Depreciation is a timing benefit, not a permanent one — it lowers basis and returns as gain at sale, with the real-property portion taxed under the unrecaptured section 1250 rules and any cost-segregated personal property recaptured at ordinary rates. Losses from rental activity are passive for most owners and can be suspended rather than used. Section 1031 defers gain on an exchange of investment real property under strict 45 and 180-day mechanics; opportunity zone funds defer eligible capital gains and can exclude appreciation after a long hold. Leverage inside an IRA triggers unrelated debt-financed income. State and local rules, transfer taxes and reassessment on sale vary widely and can outweigh the federal analysis. This is a general description of mechanisms, not tax advice, and the tax code changes.
What can go wrong in the underlying asset
Direct commercial real estate concentrates several risks that listed income does not. Illiquidity: there is no bid. Selling means marketing an asset for months, and in a poor market the option to sell at a sensible price may simply not exist. Leverage: value is derived from NOI and a cap rate, so a fall in income or a rise in cap rates reduces equity faster than it reduces income, and a loan maturing into that market has to be refinanced on the terms available then, not the terms assumed at purchase. Single-tenant concentration: one building leased to one tenant goes from fully occupied to empty on a single date, and a purpose-built structure may need substantial capital before anyone else can use it. Capital expenditure: roofs, parking lots, HVAC, tenant improvements and leasing commissions sit below the NOI line, are excluded from every cap rate quoted, and are paid in cash. Operating businesses attached to real estate — hotels, gas stations, car washes — add business risk on top: there is no lease, income moves with trade, and equipment and environmental obligations arrive on their own schedule. And direct property is only truly passive with professional management, which is a recurring cost taken out of the same income everything else is measured against. Total loss of the equity is possible, and leverage makes it possible sooner.

In the Learn library: Commercial real estate.

Where commercial property is researched and financed

LoopNet

A CoStar-operated listing marketplace for US commercial property for sale and for lease, searchable by asset type and market.

Asking prices, not transaction prices

Visit LoopNet ↗
Crexi

A commercial real estate marketplace covering for-sale listings, online auctions and lease space, with broker-supplied offering memoranda.

Visit Crexi ↗
CrowdStreet

An online marketplace where accredited investors commit capital to individual commercial property deals run by third-party sponsors.

Deal-level risk sits with the sponsor; the platform is not the operator

Visit CrowdStreet ↗
Fundrise

A platform that pools retail money into non-traded real estate and credit funds, with redemptions handled through periodic windows rather than an exchange.

Share values are set by the sponsor's NAV, not by a market price

Visit Fundrise ↗

Cost segregation — frequently asked

Is cost segregation aggressive?
It is a recognised method when supported by an engineering-based study that documents what each component is and what it cost. What draws scrutiny is classification without that support. The IRS publishes guidance on how these studies are examined, and the quality of the documentation is what the examination turns on.
Where do these numbers come from in a real deal?
From the leases, the trailing operating statements, the loan term sheet and the tax return — not from a marketing package. Every metric on this page is arithmetic on inputs that can be verified in documents, which is why the diligence list matters more than the formula. A precise metric computed from an unverified input is still an unverified number.

This section is a structural reference, not investment, tax or legal advice, and nothing in it recommends buying, selling or financing any property. It contains no market quotes: no current cap rates, rents or prices, because those are negotiated privately and are not publicly quotable. Tax rules described here are general US federal mechanisms that change with legislation, and state and local rules differ. Verify anything that matters with an attorney, an accountant and an appraiser who know the specific property and jurisdiction.

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