What Is NOI (Net Operating Income) in Real Estate?

What NOI actually is

Net Operating Income is the cash a property produces from operations, before financing and before income taxes. It is the number a buyer, a seller, and a lender should all agree on if the pro forma is honest.

The formula I use with every investor client is:

NOI = Effective Gross Income − Operating Expenses

That is the whole formula. The work is in defining each side correctly.

Effective Gross Income

Effective Gross Income (EGI) starts with everything the property could bring in, then subtracts what you actually will not collect.

• Gross Potential Rent: total rent if every unit is leased at market rate every month.
• Other Income: parking, laundry, pet fees, storage, and RUBS (utility reimbursement) if applicable.
• Vacancy and Credit Loss: a realistic reduction for months a unit sits empty and for tenants who do not pay in full.

In Philadelphia, I usually underwrite vacancy at 5 to 8 percent for stabilized rowhome rentals and higher for value-add plays with tenant turnover risk. Do not use 0 percent. That is not underwriting, that is hoping.

Operating Expenses

Operating Expenses are the recurring costs of running the property. On a Philadelphia rental, that means:

• Property taxes (and any expected reassessment)
• Property insurance
• Water and sewer (if the landlord pays)
• Trash and snow, where applicable
• Gas and electric on common areas
• Property management (I underwrite this even for self-managers, so the number reflects true operating cost)
• Repairs and maintenance (routine, not capex)
• Landscaping and pest control
• Rental license renewal and Certificate of Rental Suitability administration
• HOA or condo fees when they apply

What NOI does NOT include

This is where most first pro formas fall apart. NOI excludes:

• Mortgage principal and interest. That is debt service, not an operating cost. It belongs below the NOI line.
• Income taxes. NOI is pretax.
• Depreciation. That is a tax concept, not an operating expense.
• Capital expenditures. New roof, HVAC replacement, façade repair. Most analysts treat CapEx separately as a reserve. Ignoring CapEx makes NOI look better than it is. I always show it as a below-the-line reserve so the buyer sees the real picture.

Why NOI drives everything else

Two numbers depend directly on NOI, and they are the numbers that decide whether you can buy the property and how much you can pay.

Cap Rate

Cap Rate = NOI / Purchase Price

Cap rate tells you the property's unlevered yield. It also lets you back into value. If NOI is $30,000 and the market cap rate for that neighborhood and asset class is 7 percent, the property is worth roughly $428,000. If a seller wants $600,000 for the same NOI, the cap rate implied by their ask is under 5 percent, and you need to decide whether the appreciation story justifies that.

DSCR

DSCR = NOI / Annual Debt Service

DSCR is the ratio lenders use to size an investor loan. A DSCR of 1.25 means the property produces 25 percent more income than the annual mortgage payment. If your NOI is soft, your DSCR is soft, and your loan size drops. Read my deeper guides on what a DSCR of 1.25 means and how to qualify for a DSCR loan for context.

A quick Philadelphia example

A three-unit rowhome in a stable Philly block:

• Gross Potential Rent: $54,000
• Vacancy at 6 percent: −$3,240
• EGI: $50,760
• Operating Expenses (taxes, insurance, water, management, repairs, license): $17,500
• NOI: $33,260

At a 7 percent cap rate, that NOI supports a value near $475,000. At a 6 percent cap rate, closer to $555,000. Same property, same NOI, different market read.

If you finance $400,000 at a 30-year DSCR loan with annual debt service of $28,800, DSCR is roughly 1.15. That is below what most DSCR lenders want. Either you buy at a lower price, put more cash in, raise the rents, or the deal is not a DSCR loan.

How I use NOI on every investor deal

When I underwrite for a client, NOI is not a single number. It is three numbers.

1. Trailing NOI: what the property has actually done for the last twelve months, from real bank statements or tax returns.
2. In-place NOI: what the current leases and current expenses produce, annualized.
3. Stabilized NOI: what the property will produce after the value-add plan is executed and rents are at market.

The gap between in-place NOI and stabilized NOI is where the deal lives. That gap is also where most rookie mistakes happen, because the seller's broker is quoting stabilized NOI as if it were already there.

Where sellers manipulate NOI (and how I catch it)

Every listing pro forma I read makes at least one of these adjustments. Some are honest, some are not.

Missing property management. A seller who self-manages will show zero for management fees. That is fine for their tax return, but a buyer who plans to hire a manager should underwrite an 8 to 10 percent management line even if the seller shows zero. If you plan to self-manage, still underwrite it, because your time is not free.

Understated repairs. Sellers often show two or three years of low repair numbers on a property that has a new deferred maintenance list. I underwrite repairs and maintenance at a floor of about 5 to 8 percent of EGI for a stabilized rental, higher for older Philadelphia rowhomes with original systems.

Missing vacancy. A pro forma at 100 percent occupancy is fantasy. Even a well-run building turns units. I model vacancy at 5 to 8 percent for stabilized rentals and 8 to 12 percent for value-add plays with expected turnover.

Water and utilities buried. In many Philadelphia rentals, water is on the owner. The pro forma sometimes leaves this off. Pull the actual water bills for the last 12 months and put them in.

Property taxes at current assessed value, not reassessed value. If you are buying a value-add property, the reassessment after your rehab will jump your tax bill. Model the reassessed number, not the current one.

Catching these adjustments is not being paranoid. It is the difference between buying a property that pencils and buying a property that requires a capital call in year two.

CapEx: below the NOI line, but never off the page

Capital expenditures are the big-ticket replacement items that keep a building running: roof, HVAC systems, major plumbing and electrical work, structural repairs, exterior masonry, and window replacement. Most analysts exclude CapEx from NOI because it is lumpy and uneven, but that does not mean you can ignore it.

I always model a CapEx reserve below the NOI line, usually $250 to $500 per unit per year for stabilized properties and higher for older Philadelphia rowhomes that have not been recently renovated. That reserve does not change NOI, but it changes cash flow after debt service, and it changes what the property is actually worth to a long-term holder.

If a seller's pro forma shows a healthy NOI and cash flow but the property has an original roof, original heater, and original knob-and-tube wiring, the real cash flow after CapEx is much lower than the pro forma implies.

A longer Philadelphia example: three-unit rowhome value add

Consider a three-unit rowhome under contract for $475,000 in a stable Philly block. Current owner self-manages, has held it for 15 years, and shows the following trailing numbers.

• Gross Potential Rent: $48,000 (three units at $1,333 average)
• Vacancy shown: 0 percent
• Management: 0 (self)
• Repairs and maintenance: $1,800 trailing
• Insurance: $2,100
• Taxes: $4,200
• Water and sewer: $2,400
• License and admin: $300
• Trailing NOI shown: $37,200
• Implied cap rate at asking: 7.8 percent

Looks great. Now I rebuild it as the buyer would need to underwrite it.

• Gross Potential Rent stays at $48,000 for year one, moves to $55,800 in year two after unit turns to market rent
• Vacancy at 7 percent: subtract about $3,900
• Effective Gross Income: about $51,900 stabilized
• Management at 9 percent: $4,700
• Repairs and maintenance at 6 percent of EGI: $3,100
• Insurance realistic with a small deductible: $2,400
• Taxes at reassessed value after purchase: $6,000
• Water and sewer at actual 12-month pull: $3,000
• License and admin: $500
• Stabilized NOI: about $32,200
• CapEx reserve at $350 per unit per year: $1,050 below the line

Cap rate at asking against my rebuilt NOI is 6.8 percent, not 7.8 percent. On a DSCR loan sized to $340,000 at annual debt service of $24,000, DSCR is 1.34 on my number and 1.55 on the seller's number. Both work, but only my number reflects what the property will actually do.

That difference is why NOI discipline matters. The same property is a strong 1.34 DSCR deal or a shaky one, depending on whose spreadsheet you use.

Frequently asked questions

Should property management be in NOI even if I self-manage? Yes. Underwrite it. Your time is a cost, and one day you may want to hand off management.

Do I include mortgage interest in NOI? No. Debt service is below the NOI line. NOI is a property-level metric that stays constant regardless of how the property is financed.

Do I include CapEx in NOI? Standard practice excludes CapEx from NOI and models it as a separate reserve. Just do not pretend CapEx does not exist.

What is a good cap rate in Philadelphia? It depends on the neighborhood and asset class. In stable rowhome blocks I currently see 6 to 8 percent for well-managed rentals. Higher cap rates typically mean higher risk, more capex exposure, or thinner demand.

How does NOI relate to DSCR? DSCR equals NOI divided by annual debt service. If NOI is soft, DSCR is soft, and your loan size and rate suffer. See my guide on how to qualify for a DSCR loan for the lender side.

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Related Guides

• What Is a DSCR in Real Estate?
• DSCR Loans for Philadelphia Investors
• How to Qualify for a DSCR Loan: A Step-by-Step Guide
• How to Underwrite a Philadelphia Duplex

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