Operating Expense Ratio

How the operating expense ratio works

Operating Expense Ratio = Operating Expenses ÷ Effective Gross Income

Operating expenses are the recurring costs of keeping a property open and leased: property taxes, insurance, property management, repairs and maintenance, utilities, administrative costs and replacement reserves. Effective gross income is what the property collects after vacancy and credit loss, plus other income. The ratio answers one question: of every dollar collected, how much is spent before the owner or lender sees any of it?

The other side of the ratio is the margin. Subtract the ratio from 100% and you have the share of income that becomes net operating income. A 46% ratio is the same statement as a 54% NOI margin.

What is left out

• Debt service. Principal and interest describe how the property was financed, not how it operates.
• Depreciation and income taxes. These depend on the owner's tax position, not on the building.
• One-time capital projects. A new roof is a capital expenditure. Lenders instead reserve for it with an annual allowance, which is counted. See replacement reserves.
• Non-recurring or extraordinary costs. Fannie Mae's underwriting guidance says underwritten operating expenses are those of normal ongoing operation and that non-recurring, extraordinary expenses are not included.

The denominator question

Sources do not all agree on what to divide by. Most commercial real estate references use effective gross income, as this page does. Some divide by gross potential rent or by rental income. The National Apartment Association's income and expense survey, for example, expresses expense categories as a share of gross potential rent, so its percentages are lower than the same building’s ratio on EGI. Before you compare your ratio to someone else’s, check which denominator they used.

Worked example: a 32-unit apartment building

The building has 32 units renting at $1,200 a month, plus $1,800 a month of laundry and parking income. Vacancy and credit loss is 6% of potential income. The seller’s operating statement shows the owner managing the property and doing some repairs in-house. The figures below were run through our NOI calculator.

Line	Seller’s statement	Lender’s restatement
Gross potential rent (32 × $1,200 × 12)	$460,800	$460,800
Other income ($1,800 × 12)	$21,600	$21,600
Vacancy and credit loss (6%)	−$28,944	−$28,944
Effective gross income	$453,456	$453,456
Property taxes	$71,000	$71,000
Insurance	$24,000	$24,000
Management	$0	$18,138 (4% of EGI)
Repairs and maintenance	$38,000	$46,000
Utilities	$41,000	$41,000
Reserves ($300 per unit)	$0	$9,600
Total operating expenses	$174,000	$209,738
NOI	$279,456	$243,718
Operating expense ratio	38.4%	46.3%

The management percentage, the repair figure and the reserve amount are illustrative assumptions for this example, not quotes from any lender. Nothing about the building changed between the two columns. Only the expense lines did, and the ratio moved almost eight points.

Where the 46.3% goes

• Property taxes: 15.7% of EGI
• Repairs and maintenance: 10.1%
• Utilities: 9.0%
• Insurance: 5.3%
• Management: 4.0%
• Reserves: 2.1%

Breaking the ratio into lines is more useful than the total. If utilities run well above the other buildings in your market, that line is where the owner can act. If taxes are the largest line, the lever is an assessment appeal rather than operations.

What the difference does to value and loan size

The $35,738 gap in NOI is not a small adjustment once it passes through the metrics that decide a loan:

• Value at a 6.5% cap rate: $279,456 ÷ 0.065 ≈ $4,299,000 versus $243,718 ÷ 0.065 ≈ $3,750,000, about $549,800 less. See cap rate.
• Maximum loan at a 9% debt yield floor: $279,456 ÷ 0.09 ≈ $3,105,000 versus $243,718 ÷ 0.09 ≈ $2,708,000, about $397,000 less loan.
• Coverage on $200,000 of annual debt service: 1.40x on the seller’s NOI, 1.22x on the lender’s. See DSCR.

The 6.5% cap rate, 9% debt yield floor and $200,000 debt service are illustrative inputs.

Now run the improvement case. Suppose the owner reduces the $41,000 utility line by $10,000, perhaps by billing tenants for water and sewer or by fixing a master-metered system. Expenses fall to $199,738, the ratio to 44.0%, and NOI rises to $253,718. At the same 6.5% cap rate that is about $153,800 of value from a ten-thousand-dollar change in a single line. A lower ratio is only worth something when the savings are real and documented in the operating history.

Why the ratio varies so much between properties

The ratio depends heavily on the lease structure. Under a gross lease the landlord pays taxes, insurance, utilities and upkeep out of the rent. Under a triple-net lease the tenant pays them or reimburses them, and the landlord keeps little more than management and reserves. Two properties with almost identical NOI can show completely different ratios.

Illustration	Gross lease	Single-tenant net lease
Rent collected	$300,000	$200,000
Expenses the landlord pays	$105,000	$9,000
NOI	$195,000	$191,000
Operating expense ratio	35.0%	4.5%

These are illustrative numbers. The net-leased building looks nearly eight times more efficient on the ratio, yet earns almost the same NOI. The gross-leased building simply collects more rent and pays the costs itself. That is why the ratio is a diagnostic, not a score. Compare a property to buildings with the same lease structure, the same age and the same size.

The other drivers are the ones you would expect: property type (apartments, offices and medical buildings carry more operating cost than warehouses), building age, who pays for utilities, local tax rates, and whether the property is staffed on site. A property in a high-tax county can run a ratio ten points above an otherwise identical building elsewhere without being badly run.

Why lenders care

An underwriter reads the ratio for what it says about the operating statement’s honesty. Three patterns draw attention:

• A ratio far below comparable properties. Usually a line is missing or understated, not an unusually efficient building. A self-managed property showing no management fee is the standard case.
• A ratio that jumps or falls between years. A drop right before a sale often means deferred maintenance. A jump may be a one-time cost that should be explained and normalized. Lenders look at the trailing twelve months and the prior years side by side.
• A pro forma ratio well below the historical ratio. A seller’s projection that expenses will fall ten points deserves a documented reason.

Lenders then substitute their own numbers where the statement does not meet their standards. Fannie Mae’s published underwriting for manufactured housing communities sets the management fee at no less than 3% of effective gross income, using the actual fee instead when it is higher. For small multifamily loans, the guide sets the replacement reserve at $200, $250 or $300 per unit for a property condition rating of 1, 2 or 3 respectively, or the amount required under its reserve rules if higher. Other lenders have their own standards, but the pattern is the same: the fee is charged whether or not you pay it, and the reserve is counted whether or not it is funded.

Operating expense ratio vs. similar terms

• NOI margin is the other side of the same number: 100% minus the OER.
• Net operating income is the dollar result; the ratio is the percentage view of the cost side. See NOI.
• Break-even occupancy adds debt service to operating expenses and asks how full the building must be to cover both. The ratio ignores debt entirely. See break-even occupancy.
• Cap rate and debt yield convert NOI into value and into lender return. A higher ratio lowers both numerators.
• Expense per unit or per square foot is the same cost measured against size instead of income. It is useful when comparing buildings whose rents differ.

What to watch for before you apply

• Put a management fee on a self-managed property. Underwrite your own deal with one. If you leave it out, the lender will not.
• Do not defer maintenance to flatter the ratio. It shows up in the inspection and in the property condition report, which can raise the reserve the lender requires.
• Match the period. Income and expenses must cover the same twelve months. A statement that pairs a full year of rent with nine months of expenses understates the ratio.
• Normalize one-time items with paperwork. If a $20,000 legal bill or storm repair sits in the history, document it. A lender is more likely to remove it when there are invoices.
• Check the tax line. A sale can trigger reassessment. Taxes are often the largest line, and the seller’s tax bill may not be the one you will pay.
• Know your peers. Collect two or three comparable operating statements or appraisal comparables before you defend a number.

What it means for you

The ratio is a quick way to find out whether your NOI will survive underwriting. Rebuild your statement the way a lender will, adding management, a reserve and a realistic repair figure, then compute the ratio again. If the new ratio is still comfortable against comparable properties, the NOI you quote is probably the NOI the lender will use. If it moves by several points, you have found the gap before the term sheet does. For more on how NOI feeds the loan, read what NOI is and how lenders use it and the guide to cap rates. Multifamily owners can see how these tests apply on the multifamily loans page, and when your statement is ready, send us the T-12 and rent roll and we will tell you which lender test binds. The debt yield calculator shows the loan effect of any NOI change.

Sources: Fannie Mae Multifamily Selling and Servicing Guide (underwritten net cash flow tables: stabilized operating expenses, management fee and replacement reserve rules for manufactured housing communities and small mortgage loans); National Apartment Association, Survey of Operating Income & Expenses in Rental Apartment Communities (expense categories as a share of gross potential rent). Example figures are illustrative and were computed with the BestLoanUSA NOI calculator.