what is the operating expense ratio oer 
in real estate the operating expense ratio oer is a measurement of the cost to operate a piece of property compared to the income brought in by the property it is calculated by dividing a property s operating expense minus depreciation by its gross operating income oer is used for comparing the expenses of similar properties an investor should look for red flags such as higher maintenance expenses operating income or utilities that may deter them from purchasing a specific property the ideal oer is between 60 and 80 although the lower it is the better investopedia theresa chiechi