Cap Rate and NOI Explained for Practice Owners: How to Evaluate Buying Your Building in Chicago (2026)

At some point, most successful practice owners in Chicago hear the same pitch: "Stop paying your landlord — buy your building." Sometimes it's the right move. Sometimes it's a expensive distraction from a profitable practice. The difference comes down to two numbers most owners have heard of but few can actually calculate: net operating income (NOI) and cap rate.

This guide explains both in plain language, shows how they connect to a purchase price, and walks through how a healthcare or dental practice owner should use them to evaluate a building — as an owner-occupant, which changes the math in ways most investment articles ignore.

This guide covers:

• What NOI actually measures — and what it deliberately leaves out
• What a cap rate is, and what it tells you about risk
• How the two produce a valuation, and how sellers manipulate the inputs
• The owner-occupant twist: why your practice is the anchor tenant
• What to verify in due diligence before you trust any listed NOI
• How this connects to the lease-vs-buy decision

What Is NOI — and What It Leaves Out

Net operating income is the annual income a property produces from operations, minus the costs of running it:

NOI = gross rental income + other income − vacancy allowance − operating expenses

Operating expenses include property taxes, insurance, maintenance, management, utilities on common areas, and reserves for routine upkeep. What NOI deliberately excludes is just as important:

• Debt service. NOI is calculated before any mortgage payment — it describes the property, not your financing.
• Capital expenditures. A new roof or parking lot doesn't reduce NOI in the year you pay for it, which is exactly why a building can show healthy NOI and still be a money pit.
• Depreciation and income taxes. Accounting concepts, not operations.

For a practice owner, the discipline of NOI is that it forces you to see the building as a business of its own — separate from the practice that would occupy it.

What Is a Cap Rate — Really

A cap rate (capitalization rate) is NOI divided by the purchase price:

Cap rate = NOI ÷ price

If a building produces $120,000 of NOI and sells for $2,000,000, it traded at a 6% cap. Flip the formula and you get valuation: price = NOI ÷ cap rate. That one equation is how the entire commercial market prices income property.

The intuition that matters:

• A cap rate is a risk price. Lower cap = the market sees the income as safer (strong tenant, long lease, good location), so buyers accept a lower annual yield. Higher cap = more perceived risk, so buyers demand more income per dollar of price.
• Small cap rate moves are large price moves. The same $120,000 NOI is worth $2.0M at a 6% cap but only about $1.7M at a 7% cap. When someone argues about "half a point" of cap rate, they're arguing about hundreds of thousands of dollars.
• Cap rates are set by comparable sales, not by wishful thinking. The relevant benchmark is what similar medical or flex buildings in your submarket actually traded for — not a national average from a headline.

How Sellers Dress Up the Numbers

Because price = NOI ÷ cap rate, anyone selling a building has two levers: inflate the NOI, or argue for a lower cap rate. Watch for:

• Pro-forma NOI — the income the building could produce "after lease-up," rather than what it produces today. Insist on trailing twelve months of actual results.
• Understated expenses — missing management fees, unrealistic maintenance, no reserves, or property taxes shown at the current assessment rather than the reassessment your purchase will trigger. In Cook County and the collar counties, post-sale reassessment is a real number that belongs in your underwriting, not a footnote.
• Above-market in-place rent — a building "earning" strong NOI because a related party pays inflated rent. The lease expires; the market rent doesn't lie.
• Deferred capital costs — healthy NOI sitting under a 25-year-old roof and original HVAC. That's not a 6% yield; it's a 6% yield minus the six-figure check you'll write in year two.

Every one of these is discoverable in due diligence — leases, expense records, tax history, and a proper building inspection. None of them is discoverable in the offering brochure.

The Owner-Occupant Twist: Your Practice Is the Anchor Tenant

Here's what generic investment articles miss: when a practice owner buys a building, the practice itself becomes the anchor tenant. You're on both sides of the lease — and that changes the analysis in three ways.

First, you set the rent — within reason. Your practice signs a lease with your ownership entity, typically at market rate on a NNN structure. That rent determines the building's NOI, which determines its value and what a bank will lend against it. Set it artificially high and you're overpaying yourself with taxed dollars while inflating a value no future buyer will honor; set it below market and you suppress the asset's value. Market rent, documented with comps, is the honest and the smart answer.

Second, the vacancy risk is you. The building's income is only as safe as your practice's commitment to the location. That's why owner-occupied medical buildings often trade at attractive cap rates when they sell with a long lease in place — the future buyer is buying your covenant. It's also why the purchase decision should follow the location decision, never lead it: buying the wrong location doesn't fix it, it locks it in.

Third, you capture the spread. As a tenant, the rent you pay builds your landlord's equity. As an owner-occupant, the same rent services your own mortgage, and any additional suites you lease to other tenants add income on top. Over a 10–15 year horizon, that spread — plus appreciation and principal paydown — is the real case for buying. NOI and cap rate are how you check whether you're paying a fair price for that future, or overpaying for the story.

A Worked Example

Say you're evaluating a 6,000 SF medical building in the western suburbs listed at $1.9M. Your practice would occupy 4,000 SF; a physical therapy tenant occupies 2,000 SF on a lease with three years remaining.

1. Market rent for the space, NNN, supports a combined gross income of roughly $138,000.
2. Subtract a vacancy allowance and the owner's true operating costs (including realistic reserves and post-sale tax reassessment): NOI lands near $112,000.
3. Comparable medical buildings in the submarket have traded between 6.5% and 7.25% caps. At those caps, $112,000 of NOI supports a value between roughly $1.54M and $1.72M.

The listing at $1.9M implies a sub-6% cap on honest numbers — a price the comps don't support. That's not necessarily a dead deal; it's a negotiation, and now you're negotiating from arithmetic instead of emotion. (The numbers above are illustrative, not market quotes — your submarket comps are the ones that count.)

Before Cap Rate: The Lease-vs-Buy Question

Valuation math answers "is this building fairly priced?" It does not answer "should you own a building at all?" — that depends on your practice's cash needs, growth plans, and timeline. If you're planning additional locations, capital tied up in real estate is capital not opening your next site, which is a question of expansion and portfolio strategy before it's a question of cap rates.

We've written about that decision in Is It Better to Lease or Purchase Commercial Space and, for suburban operators, in Leasing vs. Buying Commercial Space in the Chicago Suburbs. If financing is the open question, start with How Dentists Finance Their First Practice Space in Chicago.

What to Do Before You Make an Offer

• Rebuild the NOI yourself from actual leases, actual expenses, and the reassessed tax bill — never accept the brochure number.
• Pull comparable sales for medical and flex product in your specific submarket to anchor the cap rate.
• Model your own occupancy: market rent for your practice, realistic income from any other suites.
• Structure the letter of intent with due diligence and financing contingencies that give you time to verify everything above.
• Run the full lease-vs-buy comparison over a 10-year horizon — including what else that down payment could do for your practice.

Plus CRE's buyer representation practice runs exactly this analysis for dentists and healthcare providers across Chicago and the suburbs — from underwriting the real NOI to negotiating the price the numbers actually support. Talk to us before you sign a letter of intent, not after.

Frequently Asked Questions

What is a good cap rate for a medical office building in Chicago?

There is no universal "good" number — cap rates move with interest rates, submarket, building quality, and lease strength. The only meaningful benchmark is recent comparable sales of similar medical product in your specific submarket. A cap rate that looks attractive against a national average can still be an overpayment against local comps.

Does NOI include my mortgage payment?

No. NOI is calculated before debt service precisely so that buyers with different financing can compare the same property. Your mortgage enters the analysis later, when you calculate cash flow after debt.

Should my practice pay itself above-market rent to boost the building's value?

No. Inflated related-party rent creates a valuation no future buyer or appraiser will honor, and it can create tax complications. Document market rent with comparables and let the building's value rest on honest numbers.

Is buying always better than leasing for an established practice?

No. Buying wins when the location is long-term correct, the price is supported by real NOI and comps, and the capital isn't needed for higher-return uses like expansion. Leasing wins when flexibility, growth capital, or location uncertainty dominate. It's a financial comparison, not an ideology.

How does a cap rate differ from ROI or cash-on-cash return?

Cap rate describes the property independent of financing: NOI divided by price. Cash-on-cash return describes your result: annual cash flow after debt service divided by the cash you invested. Cap rate is for pricing the asset; cash-on-cash is for judging the investment with your financing on it.

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