What the 50% rule says
The 50% rule is a back-of-the-envelope estimate: approximately half of your gross rental income will be consumed by operating expenses — property taxes, insurance, maintenance and repairs, vacancy, property management, utilities (if any), capital expenditure reserves, and other recurring costs. The remaining 50% is available to cover the mortgage payment and whatever cash flow is left.
Example: a property renting for $2,000/month has roughly $1,000/month in operating expenses. If the mortgage payment (principal + interest) is $800/month, estimated monthly cash flow is about $200. Annual pre-tax cash flow ≈ $2,400.
What the 50% rule excludes
Mortgage principal and interest are explicitly not included in the 50% — those are financing costs, not operating expenses. The rule also excludes the income tax benefit of depreciation, which can make cash flow look better on an after-tax basis than it appears before tax.
The 50% is a market average. Actual expense ratios vary from 35% to 65% depending on property age, location, whether utilities are included, and how hands-on you are with maintenance. Brand-new properties with low maintenance and strong rents might run 35%; older properties or those with heavy management might run 60% or more.
Use it for screening, not underwriting
The 50% rule helps you quickly screen a list of deals: if gross rent barely covers the mortgage at 50% expenses, the deal likely won't cash flow. It's not a substitute for building a real income statement with actual expense estimates. Before buying, itemize every expense: property tax from the county assessor, insurance quotes, management fee percentages, local maintenance cost estimates, and a CapEx reserve based on the property's age and condition. A proper cash-on-cash return calculation with real numbers is the final test.
Frequently asked questions
Is the 50% rule accurate?
It's a rough heuristic. Actual expense ratios vary from about 35% to 65% depending on property type, age, location, and whether you self-manage. Use it for quick screening, then build a detailed model before buying.
Does the 50% include mortgage payments?
No. The 50% covers operating expenses only. Mortgage principal and interest are financing costs handled separately.
How does the 50% rule relate to cash-on-cash return?
The 50% rule estimates what you'll have left after operating expenses. Cash-on-cash takes the next step: subtract the mortgage payment and divide by total cash invested to measure the actual return on your equity.
Sources
Educational information and estimates only. Not tax advice. Tax rules change and vary by situation; consult a qualified tax professional before acting.