NOI Is How You Value Properties You Can Buy With Seller Financing
Net Operating Income is the most important number in commercial real estate. It is what you use to set price, validate a deal, and negotiate seller-financing terms. If you buy based on NOI - and price the seller's note accordingly - you will never overpay.
The formula is straightforward:
NOI = Gross Scheduled Income - Vacancy - Operating Expenses
That is it. No debt service. No capital expenditures. Just the income the property generates before you pay any lender - including a seller-carry note.
Why "Before Debt Service" Matters
When you acquire a property via seller financing, your debt service (the monthly note payment) is a financing cost, not an operating cost. NOI is calculated before that payment. This is critical because:
- It lets you compare deals with different capital structures fairly.
- It is the number lenders and appraisers use to set value.
- It tells you how much room you have for seller financing terms.
Worked Example - 12-Unit Acquired Via Seller Financing
The deal:
- 12 units, $900/mo market rent each
- Asking price: $900,000
- Owner free and clear, open to carrying
Step 1: Gross Scheduled Income (GSI)
12 units x $900/mo x 12 months = $129,600/year
Step 2: Effective Gross Income (EGI)
Assume 7% vacancy: $129,600 x 0.93 = $120,528
Step 3: Operating Expenses
| Expense | Annual |
|---|---|
| Property taxes | $8,400 |
| Insurance | $4,200 |
| Property management (8%) | $9,642 |
| Repairs and maintenance | $6,000 |
| Water and trash | $3,600 |
| Reserves (5%) | $6,026 |
| Total OpEx | $37,868 |
Step 4: NOI
$120,528 - $37,868 = $82,660
Using NOI to Set the Purchase Price
At a 8.5% cap rate (reasonable for B-class 12-units in most Midwest markets):
Value = NOI / Cap Rate = $82,660 / 0.085 = $972,470
The asking price of $900,000 is actually below the cap-rate-implied value. This is a deal worth pursuing.
Now negotiate seller financing:
- Price: $880,000 (slight counter)
- Down: $20,000
- Rate: 5%
- Term: 25-year amortization, 7-year balloon
- **Monthly payment:** $5,010
- **Annual debt service:** $60,120
Net cash flow: $82,660 NOI - $60,120 debt service = $22,540/year, or $1,878/month
Your cash-on-cash return on $20,000 invested: 112.7% in year one.
The Cap Rate - Seller Financing Connection
Sellers of commercial properties are often unfamiliar with cap rates. This is your advantage. When you say "I'll pay full market cap rate, but let's talk about how you want to receive the money," you open the door to seller financing.
Framing: "Based on the NOI, the market value is about $972,000. I'd like to offer $880,000 - a slight discount for condition - but I'll structure the payment as a monthly note so you earn 5% annually on the balance. Your monthly check would be $5,010."
Many commercial sellers find this more appealing than a $880,000 wire minus a 5% brokerage commission and capital gains tax.
Common NOI Mistakes to Avoid
Mistake 1: Using proforma rents instead of actual rents. Always underwrite on current leases, not projected rents.
Mistake 2: Forgetting management fees. Even self-managed properties should include a management fee - you are buying an asset, not a job.
Mistake 3: Missing the T-12. Ask for the trailing 12-month operating statement. If the seller won't provide it, that is a red flag.
Mistake 4: Ignoring deferred maintenance. A roof replacement in year two is an NOI killer. Get an inspection before you finalize terms.
In Woosung, you can enter the T-12 actuals, apply vacancy and expense assumptions, and model the seller-financed note against the resulting NOI - all in one view. This is how you walk into a negotiation knowing your exact numbers.
The Bottom Line
NOI is not complicated. It is income minus expenses, before debt service. On every commercial deal you pursue with seller financing, calculate NOI first. Then cap it to set fair value. Then structure the note to leave real cash flow on the table.
If the NOI doesn't support the note payment, renegotiate the terms - not the NOI.