Ask five owners what their property earns and you will hear five different answers, because each of them is counting something different. Net operating income (NOI) is the answer that everyone else in the deal, from the lender to the appraiser to the buyer, agrees to use: what the property itself produces in a year after paying the costs of running it, and before debt, income taxes or big capital projects. It is also the most fragile number in real estate accounting. One misfiled roof repair or one month of uncollected rent can move it by thousands of dollars, and at a typical cap rate each of those dollars is worth far more than a dollar on the sale price. Getting it right is bookkeeping work first and investment math second, which is why the practical fix almost always sits in specialized property accounting.
What Net Operating Income Is
Fannie Mae’s multifamily guide defines underwritten net operating income in a single sentence: effective gross income less operating expenses, measured for the property as a whole. Everything in that sentence matters. Effective means the rent you actually expect to collect, not the rent on the lease list. Operating means the costs of running the building day to day. What is missing from the sentence matters just as much: there is no mortgage payment, no depreciation and no income tax in it. Investopedia’s explanation says the same thing, describing net operating income as a before-tax figure that leaves out loan principal and interest, capital expenditures, depreciation and amortization.
The formula
NOI = effective gross income − operating expenses
Effective gross income = potential rent − vacancy, concessions and bad debt + other income
Because the figure ignores how the property is financed, two owners with the same building and very different loans should report the same net operating income. That is the whole point. It lets a buyer compare your fourplex with someone else’s without guessing at your loan terms, and it lets a lender ask a clean question: does this property earn enough to carry a mortgage?
It also explains why landlords, HOA boards and property management companies all meet this number sooner or later. An owner wants it on the owner statement. A board reviewing a commercial unit or a rental portfolio wants it in the budget. A manager preparing for a refinance gets asked for it by the bank before anything else.
How to Calculate Net Operating Income, Step by Step
Here is a worked example with deliberately round numbers: a 12-unit apartment building, every unit renting for $1,500 a month. These are made-up figures for teaching, not client data and not market benchmarks.
- Start with potential rent. 12 units × $1,500 × 12 months = $216,000. This assumes full occupancy and full payment.
- Subtract the losses. Vacancy of 5% ($10,800), concessions of $1,200 and bad debt of $2,000 come off the top, for $14,000 in total.
- Add other income. Laundry, parking and pet fees of $6,000 a year. Effective gross income is now $208,000.
- List operating expenses. Property taxes, insurance, management, repairs, utilities, contract services and administration add up to $84,080.
- Subtract. $208,000 − $84,080 = $123,920. That is the net operating income.
| Line item | Annual amount | Note |
|---|---|---|
| Potential rent | $216,000 | 12 units × $1,500 × 12 |
| Vacancy (5%) | −$10,800 | Assumed rate |
| Concessions | −$1,200 | Free-rent incentives |
| Bad debt | −$2,000 | Uncollectible rent |
| Other income | +$6,000 | Laundry, parking, pet fees |
| Effective gross income | $208,000 | |
| Property taxes | −$24,000 | |
| Insurance | −$9,600 | |
| Management fee | −$12,480 | 6% of effective gross income (assumed) |
| Repairs and maintenance | −$14,000 | |
| Utilities (owner-paid) | −$12,000 | Water, sewer, common areas |
| Contract services | −$8,000 | Landscaping, trash, pest control |
| Administration and accounting | −$4,000 | |
| Total operating expenses | −$84,080 | |
| Net operating income | $123,920 | Effective gross income minus expenses |
One honest caveat before moving on: the number is only as reliable as the monthly close behind it. If the bank accounts were not reconciled or a vendor invoice landed in the wrong month, the arithmetic above will be perfect and the answer will still be wrong. That is the job of monthly accounting, and it is where most of the trouble below begins.
What Goes Into Net Operating Income and What Stays Out
The dividing line is simple to state and surprisingly easy to blur in practice: a cost belongs in net operating income if it is needed to run the property as it stands today, and it stays out if it depends on who owns the property, how they financed it, or how their tax return is built.
| Item | In or out | Why |
|---|---|---|
| Property taxes and insurance | In | Every owner of this building pays them |
| Management fee | In | Running the property has a cost whoever does it |
| Repairs and maintenance | In | They keep the property in its current condition |
| Mortgage principal and interest | Out | Depends on the owner’s financing, not the property |
| Depreciation | Out | A tax recovery of cost, not cash spent this year |
| Income taxes | Out | Depend on the owner’s personal or entity situation |
| Capital expenditures | Out | One-time investments that add value or extend life |
The repair-versus-improvement line comes straight from tax rules. IRS Publication 527 treats repairs that keep property in good working condition as deductible in the year you pay for them, while improvements that add value or extend the useful life are capitalized and recovered through depreciation over time. Residential rental buildings are depreciated over 27.5 years under that publication. Net operating income borrows the same logic: a recurring repair is an operating cost, a new roof is an investment.
Replacement reserves deserve a mention here, because they sit on the border. Lenders commonly deduct a reserve for future replacements below net operating income, not inside it. Fannie Mae’s underwriting worksheet subtracts a replacement reserve of at least $200 per unit from underwritten net operating income to reach net cash flow, whether or not the borrower actually funds an escrow. That is one more reason to keep the two figures in separate lines on your reports.
Seven Mistakes That Distort Your Number
These are the errors that show up again and again when someone hands a set of books to a lender, an appraiser or a buyer’s accountant. Each one can go in either direction, and each one is easy to miss from the inside.
1. Mixing capital expenditures with repairs
Expense a $45,000 roof replacement in the year you pay for it and the building looks like it earned $45,000 less than it did. Book a $1,800 patch as a capital improvement and you flatter the number by hiding an ordinary cost. Use the Publication 527 test from above: does the work restore what was already there, or does it improve or extend the property? When a job is a mix, split the invoice and keep the paperwork.
2. Treating vacancy as only the empty units
Physical vacancy counts the units nobody lives in. Economic vacancy also counts the units that are occupied but not paying, the free months offered to sign a lease and the balances that will never be collected. Fannie Mae’s income analysis deducts physical vacancy, concessions and bad debt as three separate steps for exactly this reason. A building that is 100% occupied can still lose real money to the second and third. A current rent roll and an aged receivables report are the raw materials.
3. Mixing cash and accrual timing
Under the cash method, IRS Publication 538 explains, you generally report income when you receive it and deduct expenses when you pay them; under the accrual method you record them when earned or incurred. A property that pays its annual insurance premium in December and its property taxes in one lump sum can show a wildly high expense month followed by eleven clean ones. Net operating income for a 12-month period should reflect a full year of costs, no more and no fewer. If your books mix both, see our guide to cash basis vs. accrual accounting.
4. Adding back owner expenses that were never the property’s
Small owners often run personal costs through the property account: a vehicle, a family phone plan, a home-office slice of the internet bill. Removing them is legitimate, and sellers do it to show what a new owner would earn. The mistake is going further and adding back costs that any operator would have, such as the owner’s own unpaid time managing the building. Every add-back needs a receipt and a reason, because the other side will test it.
5. Leaving one-time items in the number
An insurance claim payout, a lease-termination fee, a legal settlement or a one-time emergency bill tells you about last year, not next year. Fannie Mae’s guidance is explicit on both sides: other income should leave out one-time extraordinary items, and unusual non-recurring expenses are kept out of the expense side too. Keep them in the general ledger, flag them and show a normalized figure next to the reported one.
6. Skipping the management fee when the owner self-manages
If you manage your own building and pay yourself nothing, your books look richer than the property really is, because the next owner will pay someone. Fannie Mae’s underwriting instructs lenders to use the greatest of a minimum percentage of effective gross income, the actual fee or the appraiser’s concluded market fee. Even if you never send yourself an invoice, a fair management cost belongs in the calculation you show to a buyer or lender.
7. Letting debt costs creep inside
Loan interest, points and principal sometimes get coded to a utility or repair account by mistake, or show up in a catch-all account such as “other expenses.” Interest is the usual offender because it arrives on the same bank statement as everything else. A clean chart of accounts, reviewed at each close, keeps financing costs below the net operating income line where they belong. Our explanation of the financial statements property managers prepare shows how those sections are laid out.
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Net Operating Income vs. Cash Flow vs. Net Income
People use these three terms as if they were interchangeable. They answer different questions, and confusing them is how a profitable-looking building ends up short of cash. Using the example building and an assumed annual loan payment of $72,000, here is how they separate.
| Measure | Starts from | Example | Question it answers |
|---|---|---|---|
| Net operating income | Effective gross income minus operating expenses | $123,920 | What does the property itself earn? |
| Cash flow before taxes | Net operating income minus debt service and reserves | $49,520 | What is left for the owner after the lender? |
| Net income | Revenue minus all expenses, including depreciation and interest | Needs depreciation and the interest portion of the loan | What does the income statement report for the period? |
The cash flow figure above equals $123,920 minus $72,000 of loan payments minus $2,400 of reserves ($200 a unit), which gives $49,520. Net income cannot be computed from these inputs alone because it depends on depreciation and on how much of each payment is interest, and both come from outside the operating books. For the statement view, read our post on the income statement for a rental property, and for the owner’s bottom line, see rental property cash flow.
From Net Operating Income to Value
Appraisers and buyers turn net operating income into a price with one division: value equals net operating income divided by the capitalization rate, or cap rate. The cap rate is the return a buyer requires from a property of that type and location. A higher rate means a lower price for the same income, and a lower rate means a higher one.
Run the example through it: $123,920 divided by an assumed 6.5% is roughly $1,906,000. The part to remember is the leverage. At that assumed rate, $1,000 of annual NOI supports about $15,385 of value, so a $5,000 expense that never reached the ledger overstates the price by about $76,923. The lesson is that a bookkeeping error is also a valuation error.
Why Expenses Are Squeezing Net Operating Income Right Now
On the revenue side, rent growth has to fight for every dollar. On the expense side, one line has moved faster than the rest: insurance. The National Apartment Association’s Premium Pulse report, published in March 2026, says national same-store benchmarking data show annual property insurance cost per apartment unit climbing from $502 at the start of that stretch (2021) to $777 by 2024, a 55% increase. It was not a steady climb: 2022 brought an 11% rise, 2023 a 25% jump and 2024 another 12%.
The same report, citing Federal Reserve data, puts insurance at 1.95% of multifamily revenue in 2000 and 4.78% in 2024. Insurance used to be a line you renewed and forgot. Today it is a budget item that can swing NOI by itself. In the example building, a 25% premium increase on the $9,600 policy adds $2,400 of expense, which at the assumed cap rate takes about $36,923 off the indicated value. Because the NAA figures are multifamily averages, your own premium may behave differently, so check renewal quotes instead of assuming a trend.
A second, separate point on depreciation, because the tax news has made it a common question. Congress made the 100% first-year bonus deduction permanent for qualified property that an owner acquires after January 19, 2025, and the IRS issued interim guidance in Notice 2026-11, summarized in its news release. That changes the tax bill for eligible owners. It does not change net operating income, because depreciation was never part of that number, whether it is spread over decades or taken in year one. The building itself is depreciated over 27.5 years under Publication 527, and whether any component of a particular property qualifies for the faster deduction is a question for a CPA. This is general information, not tax advice.
How Property Ledger Solutions Helps with Net Operating Income
Our firm does accounting, not property management, and this is work we do month after month. We classify each expense where it belongs, separate repairs from capital items, keep financing costs out of operating accounts, reconcile the bank and trust accounts so the income is real, and produce the statements, owner statements and cash flow reporting that turn the books into a number your owner, board or lender can trust. To your clients and tenants, we’re simply the accounting support behind you — the relationship stays yours.
If you manage a portfolio, a condominium or an HOA, start with our property management accounting and monthly accounting services. If you are a landlord or an investor who wants clean books behind your own properties, begin at our home page and read how monthly accounting works. Either way, a free consultation costs nothing and carries no obligation: use the contact form or call (954) 261-1022. We also speak Spanish.
Net Operating Income FAQ
Does net operating income include the mortgage payment?
No. Principal and interest are financing costs, so they sit below net operating income, in the cash flow calculation.
Is depreciation part of net operating income?
No. Depreciation is a tax recovery of the cost of the building, not an operating cost of the year, so it is excluded, even in a year when an owner claims a large first-year deduction.
Is net operating income the same as profit?
Not quite. It is operating profit before debt, income taxes and capital expenditures. Net income on an income statement also reflects depreciation and interest, so the two figures usually differ.
What is a good net operating income?
There is no universal target. The useful comparison is against the same property’s own history, its budget and similar buildings in the same market, with both calculated the same way.
How can I improve net operating income?
Raise effective gross income by reducing vacancy and collection losses and adding fair ancillary income, and control costs you can actually influence, such as insurance shopping, vendor contracts and preventive maintenance. Cutting necessary repairs tends to lower income later.
How often should it be calculated?
Monthly, from a closed set of books, with a trailing twelve-month view. A single month is too noisy, because annual bills land in one period.
Related reading: Income statement for a rental property · Rental property cash flow · Rent roll · Owner statements explained.