The Rental Cash-Flow Model: Cap Rate, Cash-on-Cash, and DSCR

A buy-and-hold rental is a slower game than a flip, and the model that governs it is a rental cash-flow model: what the property earns, what it costs to operate and finance, and what is left over each year. Three ratios turn that into a decision, and they are the same three every lender and seasoned investor will ask you for: cap rate, cash-on-cash return, and DSCR. This guide builds a rental cash-flow model line by line on a Texas foreclosure and shows why buying below market is what makes the ratios work at today's rates.

This is general information, not legal or financial advice.

The figures are one illustration. Swap in your own rent, expenses, and financing and the same three ratios will tell you whether the deal holds.

Income minus expenses: net operating income

Every rental model starts with net operating income, or NOI: gross rent minus operating expenses, before any loan payment. NOI is the property's own earning power, independent of how you finance it, which is why cap rate and DSCR are both built on it.

Take a house bought out of foreclosure for $200,000 that would sell for about $260,000 on the open market. That below-market basis is the whole reason the numbers below work; buy the same house at retail and the ratios fall apart. It rents for $2,300 a month.

Note what NOI includes that beginners leave out: reserves for maintenance and vacancy. A rental does not stay full and repair-free every year. Modeling those reserves is the difference between a number you can trust and a number that looks good until the first turnover.

Cap rate: the unleveraged yield

The capitalization rate is NOI divided by the purchase price. It measures the property's yield as if you paid cash, so it lets you compare two properties on equal footing regardless of financing.

• NOI of $16,732 divided by a $200,000 purchase is a cap rate of about 8.4%.

Because the house was bought below market, the cap rate is measured against a low basis, which lifts the yield. Had you paid the $260,000 retail value for the same rent and expenses, the cap rate would fall to about 6.4%. Same house, same income, and a full two points of yield lost purely to the entry price. This is the quiet math behind why disciplined landlords buy distressed inventory.

Cash-on-cash: the return on your money

Cap rate ignores financing, but you do not. Most buy-and-hold investors put money down and borrow the rest, so the return that matters to your bank account is the cash-on-cash return: annual pre-tax cash flow divided by the cash you actually invested.

Finance the $200,000 purchase with 25% down and a 30-year loan:

Cash flow of $4,144 on $56,000 invested is a cash-on-cash return of about 7.4%. That is a solid figure in a high-rate environment, and again it exists only because the entry price was low. At the retail basis, the same rent would not cover the larger loan and the cash flow would turn negative.

DSCR: the test the lender runs

Before that loan is approved, the lender applies the debt-service coverage ratio: NOI divided by annual debt service. It answers one question, which is whether the property earns enough to safely cover its own payment. Most rental lenders want at least 1.20.

• NOI of $16,732 divided by debt service of $12,588 is a DSCR of about 1.33.

At 1.33 this deal clears the bar with room to spare, so the financing modeled above is realistic rather than wishful. Compare that to a high-leverage cash-out on an expensive house, where the DSCR often falls below 1.0 and the loan you modeled is not the loan you get. DSCR is where a rental model meets reality, and buying below market is what keeps it on the right side of the line.

Key takeaway. Cap rate, cash-on-cash, and DSCR are three views of the same deal: yield on the asset, return on your cash, and safety of the debt. At current rates, all three lean on the same lever, a low entry price, which is why buy-and-hold investors treat foreclosures as a primary source of inventory.

Quick screens before the full model

You will look at far more properties than you buy, so a fast screen saves the full model for deals that deserve it. The best known is the 1% rule: monthly rent should be at least 1% of the purchase price. On a $200,000 purchase that means about $2,000 a month; this house rents for $2,300, so it passes with room to spare. The rule is crude and it ignores taxes, which run high in Texas, but as a first filter it quickly rejects the properties whose rent is too thin to ever cover a mortgage plus expenses plus reserves.

Treat the 1% rule the way you treat the 70% rule for flips: a screen, not a verdict. A property can pass the 1% rule and still fail the full model once high property taxes and realistic reserves are in, and a property just under 1% can work if the taxes are low or the rent has room to grow. The screen tells you what to model, and the model tells you what to buy.

The returns cash flow hides

Cash flow is the return you can see, but a leveraged rental pays you three more ways that never show up in the monthly number:

1. Loan paydown. Every payment retires a little principal. On the $150,000 loan, the tenant pays down about $1,383 of principal in year one alone, and that figure grows every year as more of each payment goes to principal instead of interest. It is a forced savings account funded by the rent.
2. Appreciation. Texas metros have a long record of rising values. A modest 3% year on a $260,000 house is about $7,800 of equity, several times the annual cash flow, though it is never guaranteed and should be treated as a bonus rather than a plan.
3. Tax treatment. Depreciation and the deductibility of expenses can shelter part of the income from tax. That is a matter for your accountant, not this model, but it is real and it favors the buy-and-hold investor.

Add the visible cash flow, the loan paydown, and a conservative appreciation estimate together and the total return on a below-market rental is usually a multiple of the cash-on-cash figure alone. This is why patient investors accept a single-digit cash-on-cash return that a flipper would scoff at: the cash flow is only the part of the return you can spend today.

A checklist before you buy to hold

Run every candidate rental through the same short list before the model even opens:

1. Anchor the rent to what comparable units actually lease for, not the top of the range.
2. Include reserves for maintenance and vacancy in NOI, every time.
3. Size the loan to a payment the NOI covers at a DSCR of 1.20 or better.
4. Judge the entry price against market value, because the cap rate, the cash-on-cash, and the DSCR all improve when the basis is low.
5. Stress the model by asking what happens if rent is 5% lower or an expense line runs high.

The rental that survives that checklist is rare, and it usually starts with an entry price the open market will not give you. Every active listing on Fclosure carries the appraisal value, the sale date, and an equity estimate, so you can spot the properties trading far enough below market to make the rental cash-flow model work, then run the three ratios before you commit a dollar.

One last discipline separates investors who build a portfolio from those who buy one underperforming rental and stall: revisit the model after you own the property. Rents change, tax assessments rise, and insurance costs move, so the cap rate and cash-on-cash you underwrote in year one are not the numbers you live with in year three. Re-run the model annually against actual rent and actual expenses. It tells you when to raise rent, when to refinance, and when a property has quietly stopped earning its place in the portfolio and should be sold. A rental model is not a one-time calculation you do before buying; it is the instrument panel you read for as long as you hold.

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