Expected empty time/unpaid rent. Percentage of time property won't generate income.
% of EGI (often 8–10%). Cost to have someone else manage the property.
Small ongoing fixes vs big, infrequent items (roof/HVAC). Different types of property expenses.
Operating Expenses (OpEx)
Regular costs (taxes, insurance, utilities, management, repairs, CapEx reserve, HOA, misc). Not OpEx: mortgage, depreciation, income taxes.