Net Operating Income (NOI)

What NOI actually measures

Net operating income answers one narrow question: how much money does this building produce on its own, before anybody borrows against it? Add up everything the property collects, subtract everything it costs to run, and stop there.

NOI = Effective Gross Income − Operating Expenses

What goes in. Base rent, tenant reimbursements for common-area costs, taxes and insurance, plus parking, laundry, storage, signage and late fees — then subtract a vacancy and credit-loss allowance to get effective gross income. From that, take out property taxes, insurance, property management, repairs and maintenance, common-area utilities, landscaping, turnover costs, administrative expenses, and a replacement reserve.

What stays out, and why it matters.

• Loan payments. Principal and interest describe your financing, not the building. Leaving them out is what lets a lender compare your property against one bought all cash.
• Depreciation and amortization. These are tax entries. No money leaves the bank account, so they never touch NOI.
• Capital expenditures. A $180,000 roof replacement is a capital item, not an operating cost. An annual reserve allowance belongs in expenses; the roof itself does not.

Because NOI strips financing out, it becomes the input for almost everything else: cap rate is NOI divided by price, debt yield is NOI divided by loan amount, and the DSCR loan underwriting that decides your proceeds is NOI divided by annual debt service. Get NOI wrong and every downstream number is wrong with it.

Worked example: a 25,000 sq ft strip center

Income for the trailing twelve months:

• Scheduled base rent — $412,500
• Tenant reimbursements (common area, taxes, insurance) — $61,000
• Other income (signage, late fees) — $6,500
• Gross potential income — $480,000
• Vacancy and credit loss (7.5%) — −$36,000
• Effective gross income — $444,000

Operating expenses for the same period:

• Property taxes — $58,000
• Insurance — $14,500
• Property management (4% of effective gross income) — $17,760
• Repairs and maintenance — $21,000
• Common-area utilities and trash — $16,300
• Landscaping, sweeping, snow removal — $9,200
• Replacement reserves ($0.20 per sq ft) — $5,000
• Administrative, legal, accounting — $6,240
• Total operating expenses — $148,000

$444,000 − $148,000 = $296,000 of NOI, on an expense ratio of 33.3%. If annual debt service on the loan is $236,800, the debt service coverage ratio is $296,000 ÷ $236,800 = 1.25. Change the NOI and that coverage number moves with it. The NOI calculator will rebuild this line by line with your own figures.

What it means for you

The NOI you submit is not the NOI a lender uses. Underwriters rebuild it: they apply a market vacancy factor even if the building is full, add a management fee even when you self-manage, and insert a per-unit or per-square-foot reserve whether or not you fund one. That rebuild almost always lands lower than the seller's number, and lower NOI means smaller loan proceeds.

So underwrite it yourself first, conservatively, before you fall in love with a price. If your own NOI still supports the debt, you are negotiating from solid ground. When you are ready to test it against real terms, put your figures into a commercial real estate loan application and see what the coverage actually supports.

What to watch for

• The missing-management-fee trick. An owner who self-manages often shows zero management expense, and reserves are quietly dropped too. On this strip center, removing the $17,760 fee and the $5,000 reserve lifts NOI from $296,000 to $318,760. At a 7% market cap rate that inflates the value from about $4,229,000 to about $4,554,000 — roughly $325,000 of asking price built on $22,760 of expenses that do not disappear just because they are not written down.
• Pro forma rent dressed as actual rent. If the rent roll shows a unit vacant and the income statement shows it paying, you are looking at a projection. Tie every dollar back to the T-12 and the rent roll.
• One-time income inflating the top line. Lease termination fees, insurance settlements, and back-rent catch-ups are not recurring. Strip them out before you capitalize anything.
• Capital work hidden in repairs. A $60,000 parking lot resurfacing booked as maintenance suppresses NOI this year and misleads next year. Reclassify it, then fund a reserve instead.
• Taxes reassess after a sale. In many jurisdictions the purchase resets the assessed value. The seller's tax line may understate your first-year expense substantially — check the local reassessment rule before you trust the NOI.

Does NOI include the mortgage payment?

No. Principal and interest are excluded on purpose. NOI is meant to describe the property's earning power regardless of who owns it or how they financed it, which is what makes it comparable across deals. Subtract debt service from NOI and you get cash flow before taxes, which is a different number entirely.

Is NOI the same as cash flow?

No. NOI sits above debt service and above capital spending. Actual cash flow is NOI minus loan payments minus whatever capital projects you fund that year. A property can show healthy NOI and still distribute almost nothing if the debt is heavy or the roof is due.

What is a normal operating expense ratio?

Operating expenses commonly run about 30–40% of effective gross income for multifamily and 25–35% for net-leased retail or industrial, though older buildings, master-metered utilities, and high-tax jurisdictions push that higher. A ratio far below the local norm usually means an expense line is missing, not that the building is unusually efficient.