Cash-on-cash return answers one narrow question: for every dollar of cash you put into a rental, how many cents of cash came back to you this year, before income taxes. It ignores appreciation, loan paydown, and tax effects on purpose. That narrowness is the point. A property can look great on paper equity and still leave you covering a shortfall every month, and cash-on-cash is the number that catches it.
The trouble is that the number is easy to flatter. Skip the vacancy allowance, skip the capital reserve, count only the down payment as the cash you invested, and a mediocre deal prints a double-digit return. Below is the formula, then a hypothetical duplex worked two ways, the flattering way and the honest way. The same building lands at 12.3% or 6.0% depending on which lines you respect.
The formula and the two numbers it needs
Cash-on-cash return = annual pre-tax cash flow ÷ total cash invested × 100
Both inputs have precise meanings, and every flattering calculation cheats on at least one of them. The numerator is what the property left in your pocket after every operating cost and the full mortgage payment, principal included. The denominator is every dollar that left your pocket to get the property to its first rent check, not the down payment alone. If you want to run your own deal while you read, the cash-on-cash calculator does the arithmetic for free.
What counts as cash invested
The denominator is total cash out of pocket through the day the property is ready to rent. Three buckets cover most purchases:
- Down payment. On an investment property loan this is typically 20% to 25% of the purchase price, and it is the only line most back-of-envelope calculations remember.
- Closing costs. Lender fees, points, title, appraisal, and prepaid taxes and insurance usually add 2% to 5% of the purchase price on an investment loan. Closing costs on investment property walks every line item and its tax treatment.
- Make-ready costs. Paint, locks, the water heater the inspector flagged: whatever cash the property absorbs before a tenant can move in belongs in the denominator, because it came out of the same pocket the down payment did.
The common cheat is dividing by the down payment alone. On the duplex below, that quietly deletes $13,500 of real invested cash, about 14% of the total, and inflates the result to match.
What counts as annual cash flow
The numerator is what the property put in your pocket over twelve months, before income taxes. Start with gross scheduled rent and subtract four things:
- A vacancy allowance. Even a well-run unit turns over, and an empty month is a cost whether or not it has a receipt. A 5% allowance is a common planning figure for a stable long-term rental; vacancy rate math covers how to size it for your market.
- Operating expenses. Property taxes, insurance, repairs and maintenance, utilities you cover, lawn and snow, and management if you pay for it. If your books already sort every expense into Schedule E categories, this is a five-minute pull; the rental property accounting guide covers that setup from scratch.
- A capital reserve. The roof, the furnace, and the water heater arrive on their own schedule, so set aside a planning line for them. Five to ten percent of gross rent is a reasonable starting range. CapEx vs OpEx explains which costs belong in this bucket rather than in repairs.
- Debt service. The full mortgage payment, principal and interest. If your taxes and insurance are escrowed into the payment, count them once, either inside the payment or as their own lines, never both.
A capital reserve is a planning number, not a tax deduction. You set the cash aside now; the tax treatment happens later, when the roof is actually replaced and depreciated. Keep the planning number and the tax number separate in your books.
A worked example: a $340,000 duplex
Say you buy a duplex for $340,000 with 25% down and a 30-year loan at 7% on the remaining $255,000. The payment on that loan is $1,697 a month, or $20,364 a year. Each unit rents for $1,750 a month. First, the cash invested:
- Down payment at 25%: $85,000
- Closing costs: $7,400
- Make-ready repairs before the first tenant: $6,100
- Total cash invested: $98,500
Then the annual cash flow, the honest version:
- Gross scheduled rent: $3,500 a month, $42,000 a year
- Vacancy allowance at 5%: −$2,100, leaving $39,900
- Operating expenses: −$11,150 (property taxes $4,400, insurance $1,750, repairs and maintenance $2,400, water, sewer, and trash $1,900, lawn and snow $700)
- Capital reserve: −$2,500
- Debt service: −$20,364
- Annual pre-tax cash flow: $5,886
Cash-on-cash return: $5,886 ÷ $98,500 = 6.0%. In monthly terms, about $490 in your pocket before income taxes.
Now the flattering version you will see in listing pro formas. Drop the vacancy allowance, drop the reserve, and divide by the down payment alone: $42,000 of rent minus $11,150 of expenses minus $20,364 of debt service leaves $10,486, and $10,486 ÷ $85,000 = 12.3%. Same building, same loan, same tenants. The 6.3-point gap is nothing but deleted lines. More than half of the advertised return was never real.
Cash-on-cash vs cap rate
Cap rate divides net operating income by the purchase price, and by convention NOI stops before both the mortgage and the capital reserve. So cap rate describes the building while cash-on-cash describes your deal. On the duplex above, NOI is $39,900 of effective rent minus $11,150 of operating expenses, or $28,750, and $28,750 ÷ $340,000 is an 8.5% cap rate. The cap rate calculator runs that version, and NOI vs cash flow walks one property through both numbers and the gap between them.
From the 8.5% cap rate to the 6.0% cash return is two subtractions. The loan first: annual debt service divided by the loan amount, $20,364 ÷ $255,000, is an 8.0% debt constant, almost exactly the building's own yield, so the financing roughly breaks even on this deal. Borrow at a constant below the cap rate and the spread lifts your cash return; borrow above it and the debt drags the return down. The capital reserve does the rest: $2,500 against $98,500 of invested cash is 2.5 points. NOI ignores the roof by convention. Your bank account does not.
What a good cash-on-cash return looks like
There is no universal benchmark, and anyone quoting one is selling something. At current investment-loan rates, most financed buy-and-hold deals that survive an honest worksheet land between 4% and 8%. Below 3% financed, the deal is a bet on appreciation and rent growth, which can be fine if you are making that bet on purpose. A double-digit number that survives vacancy and reserves usually carries its explanation with it: a rougher property, a tougher tenant pool, or thin comps.
Two comparisons matter more than any benchmark. First, the same cash parked elsewhere: a treasury yield arrives without 2 a.m. phone calls, but it also arrives without loan paydown, depreciation, or a building that can raise its own rent, none of which cash-on-cash counts. Second, your own property against itself, year over year. A number that slides from 6% to 4% on the same denominator is an early warning about creeping expenses or flat rents, and it shows up in this metric a full season before it shows up in your stress level.
Year one distorts the number, and your books decide the rest
Year one is the worst year to judge a property on cash-on-cash. The numerator absorbs a partial year of rent, the surprises the inspection missed, and the turnover you inherited, while the denominator carries closing costs and make-ready at full weight. Run the number anyway, then trust years two and three. The opposite distortion arrives later: the denominator stays frozen at your historical cash while rents climb, so a property held ten years can show a heroic cash-on-cash figure while the equity trapped inside it earns very little. At that point return on equity is the better question, and when to sell a rental works through it.
The denominator, at least, is settled the day you close. The numerator has to be earned all year, twelve months of rent and every expense, each one captured and categorized, because a single forgotten $800 plumbing bill moves this duplex's return by eight-tenths of a point. I self-manage my own small portfolio from two time zones away, and I built rents.ai because my spreadsheet kept dropping exactly those entries. Its ledger filters by property and date range, shows cash-on-cash for the period you select, annualized and labeled as such, and exports the whole year to CSV for your CPA or your own model. It will not pull transactions from a bank feed, because there are none; you record expenses yourself or import a CSV, and the metric stays exactly as honest as the ledger underneath it. An honest 6% beats an imaginary 12% every year you own the building.