What Is Net Operating Income (NOI)?

Net operating income is calculated in two steps. First, build the income side: gross potential rent (all units at market rent) plus other income such as parking, laundry, late fees, and pet fees. Subtract vacancy and credit losses to arrive at effective gross income. Second, subtract all operating expenses. What remains is NOI.

Operating expenses cover property management fees, insurance, real estate taxes, repairs and maintenance, landscaping, and any utilities the owner pays. What the formula excludes is just as important: mortgage payments, capital expenditures, depreciation, and income taxes are all left out. NOI measures how the property itself performs, independent of how it is financed.

The exclusions are deliberate. Debt service varies by buyer: a buyer putting 30% down faces very different mortgage payments than one using 65% leverage, but the property produces the same income either way. Stripping out the mortgage lets the market price the asset based on its own fundamentals, not on any single buyer's financing structure.

Capital expenditures are also excluded. A roof replacement or HVAC upgrade is a real cost, but it is lumpy and unpredictable rather than recurring. CapEx belongs in a separate reserve analysis. Its absence from NOI is not an accounting shortcut; it is a design choice that keeps the income statement focused on ongoing operational performance.

Depreciation and income taxes depend on each investor's personal tax position. They have no place in a property-level metric that needs to be comparable across buyers with different structures and cost bases.

Before a lender approves a multifamily loan, they divide NOI by the property's annual debt service. That ratio is the debt service coverage ratio (DSCR). Fannie Mae's Multifamily Guide sets a minimum DSCR of 1.25× for Tier 2 market-rate loans: the property must produce at least $1.25 in NOI for every $1.00 in debt payments. Higher-risk loan products require 1.35× or more.

If NOI falls short of the DSCR threshold, the loan amount is reduced, the buyer contributes more equity, or the deal does not close. This makes accurate NOI underwriting one of the most consequential steps in any multifamily acquisition.

The income capitalization approach values a property by dividing its NOI by the prevailing market cap rate. A property generating $120,000 in annual NOI in a market where similar assets trade at a 6% cap rate carries an implied value of $2,000,000 ($120,000 divided by 0.06). This is the formula commercial appraisers, buyers, and lenders use to convert income into value.

The multiplier effect runs in both directions. Grow NOI by $10,000 per year and you add roughly $167,000 to value at a 6% cap rate. Let NOI erode by the same amount through poor management, deferred maintenance, or excess vacancy and the implied value falls by the same.

Two properties charging identical rents can show very different NOI figures depending on how well they are managed. Excess vacancy, deferred maintenance, inefficient insurance coverage, or rents stuck below market all compress NOI without showing up in a rent roll at first glance. The gap between a property's current NOI and what it could produce under competent management is what multifamily value-add operators are paid to close.

At EagleCap, we underwrite that gap from the bottom up: current collections, current vacancies, current expense line items compared against market benchmarks. The underwrite is not a projection of what we hope will happen. It is a description of what needs to change and how much each change is worth in dollars of NOI and implied value.