Key takeaways:
- NOI equals effective gross income minus the recurring operating expenses required to run a property.
- Property taxes and insurance reduce NOI. Mortgage debt service, owner income taxes, depreciation, and major capital expenditures generally do not.
- Before using NOI to compare or value properties, identify its period and basis, such as actual, T-12, stabilized, or underwritten NOI.
Net operating income can look like a definitive measure of property performance. Yet two owners, buyers, or lenders can calculate different NOI figures for the same building because they use different periods, assumptions, or expense classifications.
The foundation is straightforward: In real estate, the metric of NOI is a property’s effective gross income minus the operating expenses required to run it. The number helps isolate property operations from financing and owner-specific tax decisions. To use it well, however, you need to know how revenue is built, which costs belong in the calculation, and whether the result is actual, projected, stabilized, or underwritten.
This guide will answer:
- What is NOI in real estate?
- How to calculate NOI from potential rent to operating income
- A worked multifamily NOI example
- What is included in NOI and what is excluded?
- How NOI differs from cash flow, profit, and EBITDA
- How NOI and cap rate affect property value
- How actual, T-12, pro forma, stabilized, and underwritten NOI differ
- How to audit NOI before using it
- How to improve NOI through revenue and expense decisions
- Where access and security operations can affect NOI
- FAQs
Watch how ButterflyMX works:
What is NOI in real estate?
NOI, or net operating income, is a property’s effective gross income minus its operating expenses:
NOI = Effective gross income − Operating expenses
The Fannie Mae Multifamily Guide definition of NOI follows this property-level approach. NOI is calculated before mortgage principal and interest, major capital expenditures, depreciation, amortization, and owner income taxes.
That boundary is what makes NOI useful. Owners, investors, lenders, and analysts can examine the building’s operations without mixing in an owner’s financing structure or income-tax position. But property taxes are different: Real estate taxes are operating expenses, so they reduce NOI.
NOI is therefore not the same as profit or cash flow. It describes a defined part of a property’s financial performance, not every cost or obligation associated with owning it.
How to calculate NOI from potential rent to operating income
A sound NOI calculation begins with the income a property could produce and then accounts for what it does not collect. That distinction prevents gross potential rent from being mistaken for actual operating revenue.
- Start with gross potential rent. This is the scheduled rental income at full occupancy for the period being measured.
- Subtract vacancy, concessions, and credit loss. Vacancy reflects unoccupied units or spaces, concessions reduce rental income, and credit loss captures rent that is owed but not collected.
- Add recurring other income. Depending on the property, this could include parking, laundry, storage, pet fees, or similar revenue. Commercial properties may also receive reimbursement income, but its treatment depends on the leases.
- Calculate effective gross income. Effective gross income combines collectible rental income with recurring other income after vacancy, concessions, and credit loss.
- Subtract recurring operating expenses. Common lines include real estate taxes, insurance, utilities, repairs and maintenance, payroll, management fees, marketing, and administrative or professional costs.
- Label the result. Identify the reporting period and state whether the figure is actual, T-12, pro forma, stabilized, or underwritten NOI.
Keep the period consistent throughout the calculation. A month of revenue cannot be compared with a year of expenses without adjustment. The property’s chart of accounts may also vary by asset type, accounting policy, and lease structure, but the path from potential rent to effective gross income and then to NOI should remain visible.
Fannie Mae’s income-analysis framework provides a useful structure for separating effective gross income from operating expenses. It is a lender framework rather than a universal accounting policy, so property-specific classifications still require review.
A worked multifamily NOI example
Consider an illustrative annual operating statement for a 40-unit multifamily property. The figures below demonstrate the calculation; they are not market benchmarks or a forecast for a specific building.
The arithmetic is $916,000 in effective gross income minus $491,000 in operating expenses, resulting in $425,000 of illustrative annual NOI.
Two additional calculations can help with analysis. NOI per unit is $10,625 a year, or about $885 a month. The operating expense ratio is approximately 53.6%, calculated by dividing $491,000 by $916,000.
Neither figure should be treated as a universal benchmark. Utility responsibility, staffing, location, building age, physical condition, taxes, and insurance can produce very different expense structures. These metrics become useful when they are compared with the property’s history and with genuinely similar assets.
What is included in NOI and what is excluded?
NOI includes the recurring income and operating expenses associated with running a property. It generally excludes financing, owner income taxes, noncash accounting charges, and major capital projects. J.P. Morgan’s explanation of NOI and cash flow draws a similar line between property operations and costs that fall outside NOI.
The tax distinction deserves special attention. Property taxes reduce NOI because they are a cost of operating the real estate. Owner income taxes are excluded. A blanket statement that NOI excludes taxes is therefore inaccurate.
Debt service is also outside NOI. Two owners can operate identical buildings with identical NOI but have different cash flow because their loan balances, rates, and payment structures differ. Excluding principal and interest lets an analyst examine operations before those financing choices enter the picture.
Major capital expenditures, such as a substantial building-system replacement, are generally excluded because they are not recurring day-to-day operating costs. That does not make them economically unimportant. Capital spending can materially affect cash requirements, returns, and the property’s long-term condition.
Replacement reserves often sit after NOI as well. In Fannie Mae’s framework, the replacement reserve is deducted after NOI to reach net cash flow. Other lenders and investors may use different conventions, so the calculation should name the policy being followed.
Borderline items require judgment. Hardware, installation, replacement parts, service contracts, and software subscriptions may receive different treatment under an owner’s capitalization policy. Apply that policy consistently, and have property-accounting or finance professionals review classifications that could materially change the result.
How NOI differs from cash flow, profit, and EBITDA
NOI is useful precisely because it stops before several costs that matter to an owner. Cash flow, accounting profit, and EBITDA answer different questions, so none should be used as a casual substitute.
An owner can have positive NOI and still face negative cash flow after debt service, replacement reserves, or a major capital project. For that reason, any reference to net cash flow should explain which deductions were made after NOI.
Debt-service coverage ratio, or DSCR, adds another layer. A lender may deduct items such as replacement reserves from NOI to create a defined cash-flow figure and then compare that amount with debt service. Confirm the lender’s numerator, debt-service denominator, and underwriting method before relying on the ratio.
How NOI and cap rate affect property value
Under the income approach, NOI can be used with a market cap rate to estimate a property’s indicated value:
Property value = NOI ÷ Cap rate
The inverse formula is cap rate = NOI ÷ price or value. If a property has $425,000 of stabilized annual NOI and an illustrative 5% cap rate, the indicated value is $8.5 million. That is a mathematical estimate, not an appraisal, guaranteed sale price, or investment recommendation.
The same relationship can show how a sustained NOI change affects indicated value. A $25,000 annual change produces different results at different illustrative cap rates:
This sensitivity cuts both ways. An estimate can change because NOI changes, because the selected cap rate changes, or because both move at once. It is therefore important to state whether the calculation uses actual, T-12, stabilized, or underwritten NOI.
The cap rate also needs current, relevant market support. A rate drawn from a different location, property type, condition, or risk profile may not be a useful comparison. Higher NOI alone does not prove that an asset carries less risk or represents a stronger investment. For more context, see ButterflyMX’s guide to multifamily cap rates.
How actual, T-12, pro forma, stabilized, and underwritten NOI differ
Two credible parties can report different NOI figures for the same property without making an arithmetic error. They may be measuring different periods or applying different assumptions. The label tells you what kind of figure you are reviewing.
Do not compare these figures without reconciling them. Start with the historical statements, then document each change to rent, vacancy, concessions, credit loss, other income, management fees, taxes, utilities, repairs, and reserves. That bridge shows whether the difference comes from a changed period, a one-time item, or an assumption about future performance.
Underwritten NOI is especially important to label. A lender’s adjustments reflect its underwriting choices, not a universal accounting rule. Another lender, buyer, or appraiser may reach a different figure after testing the same property.
How to audit NOI before using it
Before using NOI in an offer, budget, loan package, or value estimate, trace the number back to the operating statements. A headline figure is not self-validating, even when the arithmetic is correct.
- Confirm the reporting period, property type, accounting basis, and NOI version.
- Reconcile gross potential rent to effective gross income, including vacancy, concessions, credit loss, and recurring other income.
- Test projected rent, vacancy, other-income, and expense assumptions against available property records.
- Separate recurring operating expenses from one-time items, financing costs, replacement reserves, and capital projects.
- Identify unusual changes in taxes, insurance, utilities, payroll, repairs, or management fees and determine whether they are likely to recur.
- Review multiple historical periods when available. J.P. Morgan recommends using two to three years of income and expense history for forecasting.
- Use NOI per unit and the operating expense ratio as diagnostics, then compare them with relevant properties rather than broad averages.
- For commercial property, review reimbursements, tenant improvements, leasing commissions, and other lease-specific items in their accounting context.
Finally, make sure the same classification policy is used across every period being compared. A change in accounting treatment can make NOI appear to improve or decline even when the underlying operations have not changed.
An audit cannot remove every uncertainty, but it makes the assumptions visible. Property-specific accounting, tax, lending, and valuation decisions should be reviewed with qualified professionals.
How to improve NOI through revenue and expense decisions
Improving NOI means increasing effective gross income, reducing recurring operating expenses, or doing both. The useful question is not whether one line moved in a favorable direction. It is whether the change creates a supportable, recurring improvement without shifting costs or risk elsewhere.
Review the revenue side
Revenue decisions can affect occupancy, collections, concessions, rental rates, and recurring other income. Each enters the calculation before effective gross income. A forecast should identify the affected line, the period, the evidence behind the assumption, and any cost required to achieve it.
Temporary income deserves separate treatment. A one-time payment may improve a period’s reported results, but it should not be presented as recurring NOI without a clear reason.
Review the expense side
Expense analysis may cover maintenance, utilities, staffing, property management, security, and administrative costs. Taxes, insurance, payroll, utilities, and repairs can behave differently by property and market, so there is no universal operating expense ratio or expense-reduction target.
Cutting a cost can also create a false economy. If the decision contributes to deferred maintenance, higher vacancy, greater risk, or future capital needs, the initial savings may not represent a durable NOI improvement.
Model the full effect
For each proposed change, evaluate four items separately:
- The recurring effect on revenue or operating expenses
- The implementation cost
- The capital-versus-operating accounting treatment
- The cash-flow effect after reserves and financing
Compare the actual result with the approved operating plan and document why it differed from the original assumption. That discipline keeps a temporary saving, one-time cost, or optimistic projection from being mistaken for a lasting change in NOI.
Where access and security operations can affect NOI
Access and security belong in an NOI analysis only when they connect to identifiable statement lines. Fannie Mae expense categories include locks and keys, elevators, alarm systems, security, security payroll, and patrol, providing a practical starting point for reviewing these costs.
This framework allows an owner to evaluate access technology without assuming a financial result. ButterflyMX video intercoms let residents receive visitor calls and grant access through smartphones. Property teams can remotely manage residents, visitors, credentials, and access. A property replacing a legacy telephone-entry intercom can also review its POTS line expense alongside hardware, installation, subscriptions, staffing, and maintenance.
Other property-specific options include access control, mobile and visitor access, package rooms, smart-lock integrations, and elevator controls. Elevator access controls manage access permissions; they do not replace the elevator system. Each product affects different property activities, and hardware, installation, replacement, and subscription costs may receive different accounting treatment.
The next step is to model the property’s current activity, proposed change, implementation cost, and recurring assumptions with property-management and finance review. ButterflyMX’s ROI and NOI impact calculator can help organize that property-specific scenario without promising an increase, payback period, or value gain. For broader guidance, explore the guide to the NOI of a multifamily building.
Frequently asked questions
Does NOI include property taxes?
Yes. Real estate taxes are operating expenses and reduce NOI. The tax category generally excluded from NOI is the owner’s income tax, not taxes assessed against the property.
Does NOI include mortgage payments or capital expenditures?
No. Mortgage principal, interest, and major capital expenditures are generally excluded from NOI. They still affect cash flow, capital requirements, and investment returns, so excluding them does not make them financially unimportant.
What is a good NOI for a property?
There is no universal NOI amount or ratio that makes a property good. Evaluate the figure against the property’s size, history, market, condition, capital needs, risk profile, comparable assets, and the specific NOI version being used.
How does NOI relate to DSCR?
NOI can be an input in a lender’s debt-service coverage ratio analysis. A lender may first deduct items such as replacement reserves to reach a defined cash-flow figure, so confirm the numerator, debt-service denominator, and underwriting method before calculating DSCR.
NOI becomes useful when every line can be explained. Build it from effective gross income, separate recurring operations from financing and capital items, and label the period and NOI version before comparing properties or estimating value.
The same discipline applies when evaluating access, visitor, package, turnover, or security changes. Connect each proposal to a specific revenue or expense assumption, then review its implementation cost, accounting treatment, and cash-flow effect instead of assuming an outcome.
If access operations are part of your property plan, model your assumptions with ButterflyMX’s ROI and NOI impact calculator and review the scenario with your property and finance teams.
This article is for educational purposes and is not financial, tax, accounting, lending, or valuation advice.
Get your free quote!
Fill in the form below, and we'll email you right back.
Want a free quote?
Fill in the form below, and we'll email you right back.
You’ll be redirected shortly...