Net Operating Income (NOI): Total property income minus operating expenses, before debt service and capital expenditures. This is the number lenders use to determine how much they'll lend you.
What Is Net Operating Income (NOI)?
NOI is the single most important number in commercial real estate. It determines your loan amount, your property valuation, and whether your deal closes.
If you understand nothing else about multifamily finance, understand this formula:
How Do You Calculate NOI Step by Step?
Let's break this down with a real example. Assume a 20-unit apartment building.
Step 1: Calculate Gross Potential Rent (GPR)
GPR is what you'd collect if every unit was occupied and paying full rent.
| Unit Type | Count | Monthly Rent | Annual |
|---|---|---|---|
| 1BR/1BA | 12 | $950 | $136,800 |
| 2BR/1BA | 8 | $1,200 | $115,200 |
| GPR | $252,000 |
Step 2: Subtract Vacancy and Credit Loss
No property runs at 100% occupancy. Lenders assume 5-7% vacancy even if your actual vacancy is lower.
| Gross Potential Rent | $252,000 |
| Less: Vacancy (5%) | ($12,600) |
| Less: Concessions | ($3,000) |
| Less: Bad Debt | ($2,400) |
| Net Rental Income | $234,000 |
Step 3: Add Other Income
Include all non-rent income: laundry, parking, pet fees, late fees, application fees.
| Net Rental Income | $234,000 |
| Laundry Income | $4,800 |
| Parking Income | $3,600 |
| Late Fees | $1,200 |
| Effective Gross Income (EGI) | $243,600 |
Step 4: Subtract Operating Expenses
Operating expenses include everything required to run the property. They do not include mortgage payments or capital improvements.
| Expense Category | Annual Amount |
|---|---|
| Property Taxes | $24,000 |
| Insurance | $8,400 |
| Utilities (Owner Paid) | $12,000 |
| Repairs & Maintenance | $15,000 |
| Management (8%) | $19,488 |
| Landscaping | $3,600 |
| Contract Services | $2,400 |
| Administrative | $1,800 |
| Total Operating Expenses | $86,688 |
Step 5: Calculate NOI
How Do Lenders Use NOI?
NOI feeds into two critical calculations: Debt Service Coverage Ratio (DSCR) and property valuation.
DSCR: Can You Pay the Mortgage?
Lenders require a minimum DSCR, typically 1.20x to 1.35x. This means for every $1.00 in mortgage payments, you must generate $1.20 to $1.35 in NOI.
Using our example with a $156,912 NOI and a 1.25x DSCR requirement:
This caps your mortgage payment at ~$10,461/month, which determines your maximum loan amount.
Property Valuation: The Cap Rate
At a 7% cap rate, our example property is worth:
Every dollar of NOI you can prove increases your property value by $10-15, depending on the cap rate.
$10,000 in additional provable NOI = $140,000+ in additional property value (at 7% cap).
What Destroys NOI (and Your Loan)?
Income Haircuts
If the lender can't verify your income, they'll "haircut" it. Common scenarios:
- Cash payments not deposited: You say you collected $5,000 cash. Bank shows $0. Lender credits $0.
- Section 8 in a different account: $22,000/year hitting an affiliate account. If not documented, lender credits $0.
- Inconsistent deposits: Rent roll shows $10,000/month. Bank shows $8,500. Lender uses $8,500.
Expense Add-Backs
If your expenses look artificially low, lenders will add standardized expenses:
- No management fee? Lender adds 5-8% management expense, even if you self-manage.
- No reserves? Lender adds $250-300/unit for replacement reserves.
- Below-market taxes? Lender projects post-sale tax reassessment.
What Is the Difference Between Your NOI and Lender NOI?
Lenders don't blindly accept your NOI. They adjust it to reflect "stabilized" or "underwritten" performance:
| Your T-12 | Lender Adjustment |
|---|---|
| 3% vacancy | Adjusted to 5% minimum |
| $0 management (self-managed) | Added 6% management fee |
| $0 reserves | Added $250/unit reserves |
| Cash income (unverified) | Excluded from income |
The gap between your NOI and the lender's underwritten NOI is where deals get reduced—or killed.
How Do You Protect Your NOI?
- Deposit everything. Every rent payment, every fee, every dollar of income goes through a bank account.
- Document your income mix. If you have Section 8, provide the HAP contracts. If you have commercial tenants, provide the leases.
- Keep receipts for expenses. If you can't prove you paid it, it may not count as an expense—which sounds good until you realize unrealistically low expenses trigger add-backs.
- Reconcile monthly. Your T-12 should tie to bank statements within 1-2% every month.
NOI is not what you earned. It's what you can prove you earned. The difference is your loan amount.