50% Rule for Rental Expenses

The 50% rule

The 50% rule is a quick estimate. It says operating expenses on a rental property usually eat up about half of gross rent once you add up IPTU, condominium fees, maintenance and capex reserve, vacancy, management and insurance. NOI = gross rent − 50% × gross rent and net cash flow = NOI − debt service. Take a property collecting R$ 2,200/month in gross rent. Estimated expenses come to R$ 1,100/month, which leaves R$ 1,100 of NOI before financing. The rule grew out of US small-multifamily data and leans conservative on purpose. In Brazil, expense ratios actually run lower on solid residential, where 20%–40% is more typical, but the 50% figure buys you a safety margin for quick screening when you don't yet have property-specific data.

Applications

For a fast first pass across a stack of properties, the 50% rule earns its keep. Take the asking rent, halve it, subtract the mortgage payment you expect, and check whether cash flow is even plausible. It's a guesstimate, so once a property looks promising you should swap in the real operating-expense numbers from the seller and from your own read of comparable properties.

FAQ

Is 50% always right? No, and it's meant to be conservative. New construction with no condominium and a long-term tenant might run 20%, while old buildings with high condo fees and frequent turnover can push past 50%.

Does it include financing? No. The 50% rule covers operating expenses only. Debt service is subtracted from NOI on its own to land on net cash flow.

Replace it with detailed numbers when? Before you make an offer. Pull the actual IPTU and condominium fees, the last 12 months of maintenance, and apply local vacancy data.