Operating Expense Ratio (OER)
The percentage of gross rental income consumed by operating expenses, before debt service.
Definition
OER tells you how efficiently a property runs. If your OER is 45%, then 45 cents of every dollar of rent goes to taxes, insurance, maintenance, PM fees, utilities, and other operating costs. The remaining 55 cents becomes your NOI. A low OER is a green flag for a well managed property in a stable neighborhood. A high OER is a warning sign that the property either has expensive deferred maintenance, a bad property manager, or high fixed costs like taxes and insurance relative to rent. The 50% rule you see in beginner investor content is actually just a lazy OER of 50%. In reality, well run single family rentals in the Midwest and Southeast often run 35 to 45% OER. Class C properties with heavy maintenance and Section 8 compliance costs can push 50 to 60%. Coastal California and Florida coastal properties with high insurance can exceed that.
Formula
Example
A property grosses $24,000 annually and has $9,600 in operating expenses (taxes, insurance, maintenance, PM fees, vacancy reserve). OER = 9,600 / 24,000 = 40%.
Frequently asked
What is a good operating expense ratio for rental property?
35 to 45% is typical for well run single family rentals. Above 50% signals a problem.
Does operating expense ratio include mortgage payments?
No. Mortgage payments are debt service, not operating expenses. OER is calculated before debt service.
What expenses count toward the operating expense ratio?
Taxes, insurance, maintenance, repairs, property management fees, utilities paid by owner, vacancy reserves, and HOA fees.
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