Definition
Net Operating Income (NOI) is a property’s income after operating expenses, but before debt service (principal and interest), income taxes, depreciation, and capital expenditures. NOI is the primary earnings metric used to value income-producing real estate.
Core Formula
At a high level:
- NOI = Effective Gross Income (EGI) − Operating Expenses
Step-by-step
- Potential Gross Income (market rents + other income at full occupancy)
- Minus vacancy and credit loss = Effective Gross Income (EGI)
- Minus operating expenses = NOI
What NOI Includes
NOI is meant to reflect ongoing, property-level performance. Common income and expense items include:
Typical income
- Base rent
- Other income: parking, pet rent/fees, storage, utility bill-backs, laundry, application/admin fees
Typical operating expenses
- Payroll and on-site staffing
- Repairs & maintenance and contracted services
- Utilities (owner-paid portion)
- Property taxes
- Insurance
- Management fees (third-party or imputed)
- Marketing, admin, and turnover costs
What NOI Excludes (On Purpose)
These items are excluded because they depend on the investor’s capital structure or are non-operating in nature:
- Debt service: principal and interest
- Income taxes
- Depreciation and amortization
- Capital expenditures (capex): roofs, major systems, unit renovations, parking lots, etc.
- One-time / non-recurring items (unless normalized)
Note: Some investors underwrite a “NOI after reserves†by subtracting replacement reserves (a capex allowance), but that is a convention choice—classic NOI is before reserves.
Why NOI Matters
NOI drives value because many income properties are priced off a capitalization rate:
- Value ≈ NOI ÷ Cap Rate
If cap rates are stable, increasing NOI directly increases property value. This is why operators focus on controllable levers that grow durable NOI (rents, other income, and expense efficiency).
Investor Uses
- Valuation: compare implied cap rate (NOI ÷ price) to comps and required return.
- Underwriting: test assumptions for rents, vacancy, concessions, and expenses.
- Operations: measure property performance independent of financing decisions.
- Debt sizing: lenders evaluate NOI-based coverage (see DSCR).
- Business plan clarity: identify which initiatives actually move NOI (not just revenue).
Example
A 50-unit multifamily property produces the following annual figures:
- Gross scheduled rent: $900,000
- Other income: $60,000
- Vacancy/credit loss (5%): −$48,000
- Operating expenses: −$420,000
Calculation:
- EGI = 900,000 + 60,000 − 48,000 = $912,000
- NOI = 912,000 − 420,000 = $492,000
If the property trades at a 5.5% cap rate, the implied value is: $492,000 ÷ 0.055 ≈ $8,945,455.
Common Pitfalls
- Mixing NOI and cash flow: NOI is before debt; cash flow is after debt (and often after reserves).
- Understating expenses: ignoring true payroll, maintenance, admin, or “owner-managed†shadow costs.
- Forgetting taxes and insurance resets: taxes can rebase after sale; insurance can re-rate quickly.
- Counting one-time income: late fees, lease break fees, and unusual reimbursements may not be durable.
- Ignoring capex: strong NOI doesn’t help if deferred maintenance is about to demand major spend.