What Is NOI? Net Operating Income in Plain English

If you learn one number in apartment investing, learn this one. Net operating income — NOI — is the income a property produces from operating, before any financing. It is the figure that sets what a building is worth, the figure a lender sizes a loan against, and the figure every seller in America would like to show you at its most flattering. Understanding it is most of the work of reading an offering package.

The definition

NOI is all the revenue a property collects in a year, minus all the costs of operating it. Revenue means rent actually collected plus other income — laundry, parking, pet fees, utility reimbursements. Operating expenses means what it costs to run the building: property taxes, insurance, on-site payroll, property management, repairs and maintenance, turnover, landscaping, marketing, and the utilities the owner pays.

What makes NOI useful is what it leaves out. Four things sit below the line:

• Debt service. Mortgage principal and interest are excluded, because NOI describes the building, not the buyer. Two investors can pay wildly different financing costs for the same asset; the property’s earning power does not change.
• Capital expenditures. Roofs, boilers, parking-lot resurfacing — big, lumpy, occasional spending is excluded by convention. This is the single most-abused exclusion in the business, and we come back to it below.
• Depreciation. A tax and accounting concept, not cash leaving the building.
• Income taxes. Those depend on the owner, not the asset.

The point of stripping those out is comparability: NOI lets you line up two buildings side by side on operating performance alone, regardless of who owns them or how they borrowed.

Why NOI sets the price

Commercial real estate is valued off its income. The shorthand is simple: value equals NOI divided by the capitalization rate. If a property earns $500,000 of NOI and comparable buildings trade at a 7% cap rate, the implied value is about $7.1 million. (If cap rates are unfamiliar, start with what a cap rate actually tells you.)

Turn that equation around and you see the leverage buried in it. At a 7% cap, every extra dollar of annual NOI is worth roughly fourteen dollars of value. Add $50,000 of real, durable NOI and you have created about $700,000 of value. That is the entire logic of value-add apartment investing — and it is also precisely why a pro-forma with $50,000 of imaginary NOI in it is not a small error. It is a $700,000 error.

Where NOI gets inflated

Almost nobody fabricates an NOI outright. The number gets stretched, line by line, in ways each of which is defensible on its own:

• Market rents standing in for collected rents. The rent roll shows what tenants pay. The pro-forma shows what the seller believes they could pay. The gap between the two is the most common source of a too-high NOI.
• The seller’s property-tax bill. In much of the country a sale triggers reassessment toward the new price, and taxes jump the year after closing. Underwrite the old bill and the NOI is overstated from day one — a trap we have written about at length.
• Thin or missing vacancy and credit loss. No building collects 100% of scheduled rent. Turnover, delinquency, and concessions are real. A pro-forma at 95% occupancy in a market handing out two months free is not describing next year.
• No management fee. A self-managing seller may show zero, but the next owner will pay three to four percent of revenue for professional management. Leaving it out inflates NOI on a cost the buyer will absolutely incur.
• Capital spending routed below the line. Because capex is excluded by convention, ordinary recurring work — unit turns, appliance replacement, roof patching — can be reclassified as “capital” and quietly lifted out of expenses. Nothing about the building changed; the NOI just went up.
• Optimistic other income. A new laundry contract or a valet-trash program can be legitimate. A line for revenue no one has yet collected a dollar of is a forecast wearing a financial statement’s clothes.

How we compute it

Our rule is that NOI is built from what happened, not from what could happen. We start with the trailing twelve months of actual collections and actual expenses, reconcile the rent roll against the bank deposits, reassess the taxes to our purchase price, add a full management fee whether or not the seller paid one, carry an explicit vacancy and credit-loss factor drawn from the submarket rather than the brochure, and hold back a per-unit reserve for recurring capital work even though convention lets us exclude it. The instinct underneath all of it is the same: trust the record over the projection.

The result is almost always a lower NOI than the offering package shows, and therefore a lower price we can pay. That is not pessimism; it is the arithmetic working correctly. A number that determines value at a multiple of fourteen deserves to be built conservatively — and once you have an honest NOI, the next question follows naturally: how full does this building have to stay just to cover its bills?