Net operating income is the baseline measurement of a property's profitability before financing. Once you understand it -- really understand it -- you see how every income property valuation flows from this one number.
What Is Net Operating Income?
Net operating income (NOI) is the annual income a property generates after paying all operating expenses, but before paying debt service (mortgage payments) and income taxes.
It answers: how much money does this property produce from operations, independent of how it's financed?
This is important because NOI is the same whether you bought the property in cash or financed it with 80% LTV. Financing is a choice. Operations are the property's core performance.
The NOI Formula
Where: Gross Operating Income = (Gross Potential Rent - Vacancy and Credit Loss) + Other Income Operating Expenses = All direct costs to operate the property (excluding debt service)
Let's break down each component.
Gross Operating Income
Gross Potential Rent (GPR) is what the property would earn if all units were rented at full market rent 100% of the time.
Vacancy and Credit Loss is a deduction for realistic vacancy (units sitting empty) and uncollected rent (tenants who don't pay). Most lenders and investors use 5-10% of GPR as a conservative estimate.
Other Income includes anything beyond rent: parking fees, laundry income, pet fees, storage unit fees, late charges.
Gross Potential Rent: $4,800/month ($1,200 per unit x 4) Less vacancy/credit loss (5%): ($240) Other income (laundry): $80 Gross Operating Income: $4,640/month Annual GOI: $55,680
Operating Expenses: What to Include
This is where most new investors make mistakes -- either by forgetting expenses or by including ones that don't belong.
Include these in NOI calculations:
- Property taxes
- Insurance (property and liability)
- Property management fees (even if you self-manage -- price in the cost to hire someone)
- Maintenance and repairs (use 5-15% of gross rent as an annual reserve)
- Capital expenditure reserve (roof, HVAC, major systems -- use 5-10% of gross rent)
- Utilities paid by the landlord (water, trash, common area electric)
- Landscaping and snow removal
- Pest control
- Advertising and leasing costs
Operating Expenses: What to EXCLUDE from NOI
These are NOT operating expenses for NOI purposes:
- Mortgage principal and interest payments
- Depreciation
- Income taxes
- Capital improvements (adding value, not maintaining it)
Calculating NOI: Full Example
Annual Gross Potential Rent: $55,680 Less vacancy (7%): ($3,898) Other income: $960 Annual Gross Operating Income: $52,742
Annual Operating Expenses: Property taxes: $5,200 Insurance: $2,400 Property management (8%): $4,219 Maintenance reserve (8%): $4,219 CapEx reserve (6%): $3,164 Landscaping / misc: $1,200 Total Operating Expenses: $20,402
NOI = $52,742 - $20,402 = $32,340
Cap Rate = $32,340 / $380,000 = 8.51%
NOI vs Cash Flow: The Key Difference
NOI stops before debt service. Cash flow subtracts your mortgage payment.
From the example above: NOI: $32,340 Annual mortgage payment (25% down, 7.5% rate): $25,620 Annual Cash Flow: $6,720 Monthly Cash Flow: $560
Two investors can buy the same property, generate the same NOI, and have dramatically different cash flows based on their financing. One pays cash -- all of the NOI is cash flow. One uses 75% financing -- their cash flow is much lower.
This is why cap rate (which uses NOI) is a property metric, while cash-on-cash return is an investor metric.
Cash flow vs appreciation -- which to prioritize as an investor
Full guide to cap rate in real estate
How Lenders Use NOI
Lenders use NOI to determine how much you can borrow and whether a property supports the loan. This is the foundation of DSCR (Debt Service Coverage Ratio) calculations.
If NOI = $32,340 and annual debt service = $25,620: DSCR = $32,340 / $25,620 = 1.26
Most lenders want DSCR above 1.20. This property qualifies.
How DSCR loans work for real estate investors
How to Verify a Seller's NOI Claims
Sellers sometimes inflate NOI by understating vacancies, excluding management fees, or overstating rents. Here's how to verify:
- Request 12-24 months of bank statements showing actual rent deposits
- Pull a current rent roll with lease end dates
- Compare stated rents to market rates (Rentometer, Zillow rentals, local PM companies)
- Get the actual tax bill and insurance declaration page
- Ask for the last 2 years of Schedule E from the seller's tax return
Full guide to analyzing rental properties
Get Instant NOI and Cap Rate on Any Property
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FAQ
Does NOI include mortgage payments?
No. NOI is calculated before debt service (mortgage payments). This is intentional -- it allows you to evaluate a property's intrinsic income performance regardless of financing. Mortgage payments are factored in when you calculate cash flow or DSCR.
What is a good NOI for a rental property?
"Good" is relative to the property's value. A $500,000 property with $40,000 NOI has an 8% cap rate, which is strong in most markets. For small multifamily, aim for NOI that supports at least 1.20x DSCR at current market rates.
Can NOI be negative?
Yes. If operating expenses exceed gross operating income -- which can happen with high vacancies, major unplanned expenses, or severely below-market rents -- NOI goes negative. A property with negative NOI is a cash drain regardless of how it's financed.
Why do some sellers show high NOI but the property doesn't cash flow?
Usually because the purchase price is too high relative to the NOI (low cap rate), or because financing costs are high (rising interest rates compressing spreads). High NOI and poor cash flow often means the seller is pricing for appreciation, not income. Verify the cap rate and run your own DSCR at current rates.
Should I include depreciation in NOI?
No. Depreciation is an accounting and tax concept, not a cash expense. Excluding it from NOI is standard practice. You account for physical wear through CapEx reserves (which are included in operating expenses), not accounting depreciation.