Specifically in the context of rental property which you own free and clear, your Net Operating Income (NOI) is what you have left over from your annual rental income after your have paid all of your operating and ownership expenses and before you pay taxes.
Depreciation and debt service (principal and interest) are not operating expenses.
NOI generally means, Net Operating Income.
income from property or business after operating expenses have been deducted... but before deducting income taxes and financing expenses.
Specifically in the context of rental property which you own free and clear, your Net Operating Income (NOI) is what you have left over from your annual rental income after your have paid all of your operating and ownership expenses and before you pay taxes.
Depreciation and debt service (principal and interest) are not operating expenses.