Real estate & rental
Rental Property Returns Explained: Cap Rate, Cash-on-Cash, and Cash Flow
Three numbers describe what a rental actually earns, and they answer three different questions — what the property yields, what your invested cash yields, and what hits your bank account each month. None of them is the number that lands on your tax return, and the gap between them is where most rental math goes wrong.
7 min read · Published September 2026
Key Takeaways
- Cap rate is NOI divided by purchase price — the property's yield before any mortgage. It's the number for comparing one property against another, because it ignores how each buyer happens to finance.
- Cash-on-cash return is annual pre-tax cash flow divided by the total cash you put in (down payment, closing costs, upfront repairs). It's your yield, and leverage moves it — up when the property out-earns the loan, down when it doesn't.
- Monthly cash flow is NOI minus the mortgage payment: the number that decides whether the property pays you or you pay it. The budget lines people skip — vacancy, a capex reserve, management — are exactly the ones that flip its sign.
- Financing helps only when the cap rate beats the loan's all-in annual cost (debt service divided by loan amount). Below that line, every borrowed dollar lowers your return instead of raising it.
- None of these three numbers is taxable income. Depreciation pushes the tax number below cash flow — sometimes into a loss while cash flow is positive — and mortgage principal pushes the other way: it costs cash but deducts nothing.
The numbers below are illustrative, not a real client’s — this site isn’t attached to a firm, so there isn’t one.
Three numbers, three questions
A listing that says “great cash flow!” is quoting one of three different numbers, and it rarely says which. Cap rate, cash-on-cash return, and monthly cash flow all describe what a rental earns, but they answer different questions — and buying a property because one of them looked good when you needed a different one is how bad deals get made.
| Metric | What it measures | Includes the mortgage? | The question it answers |
|---|---|---|---|
| Cap rate | NOI ÷ purchase price | No | What does this property yield, regardless of financing? |
| Cash-on-cash | Annual cash flow ÷ total cash invested | Yes | What is my invested cash earning? |
| Monthly cash flow | NOI minus debt service, per month | Yes | Does this property pay me, or do I pay it? |
Cap rate: the property’s yield, before financing
Cap rate starts with net operating income — NOI. Take a year of rent, knock off a vacancy allowance for the weeks it sits empty, then subtract operating expenses: property taxes, insurance, maintenance, and management. The mortgage is deliberately not on that list. NOI is what the property itself produces; divide it by the purchase price and you have the cap rate.
Because financing is excluded, cap rate is the one number that compares cleanly across properties and across buyers. A 5.25% cap is a 5.25% cap whether the buyer pays cash or borrows 75% — which is exactly why it’s the wrong number for predicting what lands in your bank account.
Notice what the $9,000 covers: taxes, insurance, maintenance, management, and an allowance for vacancy — everything it costs to operate the property, and nothing it costs to finance it. This same property carries through every example below.
Cash-on-cash: your yield, with the loan in the math
Cash-on-cash return divides the year’s pre-tax cash flow — NOI minus the full mortgage payment — by the total cash you actually put in: down payment, closing costs, and any upfront repairs. It answers the question the cap rate refuses to: what are your dollars earning here?
Leverage is the whole story of this metric, and it cuts both ways. Borrowing shrinks the cash you invest, but the loan payment comes out of the return. Whether that trade helps or hurts depends on one comparison: the cap rate versus the loan’s all-in annual cost — total yearly debt service divided by the amount borrowed. On a $300,000 loan at 6.5% over 30 years, debt service runs about $22,754 a year, which is roughly 7.6% of the loan. A 5.25% property financed with 7.6% money means every borrowed dollar loses about two cents a year.
Leverage didn't create or destroy anything by itself — it multiplied the spread between what the property earns (5.25%) and what the loan costs (about 7.6%). That spread is negative here, so borrowing turned a modest positive return into a negative one. Flip the spread — cheaper debt, or a property earning more than the loan costs — and the same multiplication works in your favor.
Monthly cash flow: the number that hits your bank account
Monthly cash flow is NOI minus debt service, divided by twelve. It’s the least abstract of the three: the property either deposits money into your account each month or withdraws it. Our example property withdraws — about $146 a month.
This is also the number people most reliably overstate, because the flattering version skips three budget lines. A vacancy allowance, because no unit rents 52 weeks a year forever. A capital-expenditure reserve, because the roof and the water heater are dying on a schedule whether or not you’ve budgeted for it. And management, even if you self-manage — your time isn’t free, and a deal that only works with an unpaid manager stops working the day you stop volunteering.
This property loses $146 a month in the bank account and about $10,000 a year on the tax return — and neither number was in the listing.
None of these is your taxable income
Here’s where rental math earns its reputation. The number that lands on Schedule E is none of the above: it’s NOI minus mortgage interest minus depreciation, and two forces pull it away from cash flow in opposite directions.
Depreciation pulls it down. A residential rental’s building (not the land) deducts over 27.5 years, straight line — the deduction that doesn’t feel like one, because no cash leaves when you take it. If our $400,000 property is $320,000 building and $80,000 land, that’s $11,636 a year deducted with no check written. (A cost segregation study can front-load even more of it.)
Mortgage principal pulls the other way. Of that $22,754 in year-one debt service, about $19,401 is deductible interest — but the remaining $3,353 of principal costs real cash and deducts nothing. So the tax number for our property is $21,000 − $19,401 − $11,636 = a $10,037 loss, on a property whose actual cash loss was $1,754. A property with slightly better cash flow shows the starker version: money arriving every month, a loss on the return.
One caution before spending that paper loss: rental losses are passive by default, and passive losses generally only offset passive income. Whether a $10,037 loss reduces this year’s tax bill or waits in carryforward depends on the passive activity loss rules — the $25,000 allowance, its income phase-out, and the exceptions.
Run a property through all four numbers at once
Cap rate, cash-on-cash, monthly cash flow, and taxable income — side by side, from one set of inputs.
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Sources & References
Frequently asked
Questions owners actually ask
- Is this a real client situation?
- No — the numbers below are illustrative, run through this site's own rental ROI calculator. There's no firm behind this site and no client relationship being described.
- What's a good cap rate?
- There isn't a universal one, and a cap rate quoted without context means nothing. Cap rates price risk and growth: a stable property in an expensive coastal market might trade at 4%, a rougher property in a declining market at 9%, and neither number is 'better' — the 9% is compensation for vacancy risk, deferred maintenance, and thinner appreciation. The useful comparison is against similar properties in the same market, and against what the same dollars earn elsewhere at similar risk.
- Should I include my own labor in the numbers?
- Budget for management even if you self-manage, and price your own repair work at what you'd pay someone else. If the deal only works because you mow the lawn and answer 2 a.m. calls for free, the property isn't earning that return — you are, as an unpaid employee. Pricing your labor in also keeps the numbers honest for the day you stop wanting the job.
- Is cash-on-cash return before or after tax?
- Before, as conventionally quoted and as this site's calculator computes it: annual cash flow after operating expenses and the full mortgage payment, but before income tax. The after-tax picture depends on depreciation, your bracket, and whether passive loss rules let you use a loss this year — which is exactly why cash-on-cash and taxable income diverge.
- Why is my taxable income negative when the property made money?
- Depreciation. You deduct a slice of the building's cost every year — about $11,600 a year on a $320,000 building over 27.5 years — without writing a check for it. That non-cash deduction can push taxable income below zero while actual cash flow stays positive. Whether you can use that loss against other income this year is a separate question, governed by the passive activity rules.
- Why doesn't cap rate include the mortgage?
- Because the mortgage is a fact about the buyer, not the property. Two buyers of the same building at the same price — one all-cash, one at 25% down — own an asset producing identical NOI. Leaving financing out is what makes cap rate comparable across properties and across buyers; the moment you want your return, you switch to cash-on-cash.
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Educational content only. This article is for informational purposes and does not constitute tax, legal, or financial advice. Every situation is different — consult a qualified professional before acting on anything here.