Using a HELOC for a Rental Down Payment: The Real Cost Math

A HELOC down payment does not lower the cost of a rental. It moves the down payment from your savings account to your house and charges you interest on it. The property now has to support two loans, and most listings cannot.

Here is the number that frames the rest of this post. An example $250,000 rental that shows $209 a month of cash flow on a normal pro forma loses $287 a month once the interest-only HELOC payment is counted, and $398 a month once that line starts amortizing. The deal did not change. The only thing that changed is that the full capital stack got counted.

The strategy: borrowed down payment, two loans, one property

The mechanics are simple. You open a home equity line of credit against a property you already own, usually your primary residence. You draw enough to cover the down payment and closing costs on a rental. A conventional lender writes the first mortgage on the rental for the other 75% to 85% of the price.

Lenders allow this. Funds borrowed against an asset you own are an acceptable source for a down payment on a conventional loan, provided you disclose the line and the lender counts its payment in your debt-to-income ratio. Hiding the HELOC from the first mortgage lender is mortgage fraud, so the plan has to qualify with both payments in view.

The result is a rental financed at more than 100% of its price. In the example below, a $250,000 house carries $257,500 of debt: a $187,500 first mortgage plus a $70,000 HELOC draw that covers the $62,500 down payment and $7,500 of closing costs. You have no cash in the deal. You do have two liens, two payments and two properties exposed.

That is the honest description of the move: borrowing stacked on borrowing. Cash-on-cash return stops being a useful number because the denominator is zero. A deal that earns $1 a year on no cash shows an infinite return, and a deal that loses $1 shows an infinitely bad one. The useful questions are whether the rent carries both payments and how you retire the line.

If you are still working out how much cash a first purchase needs when you fund it the ordinary way, the full cash requirement for a first rental is the baseline to compare against.

The true blended cost of capital, worked out

All rates in this post are labeled examples, not quotes. Assume a 30-year fixed first mortgage at an example 7.25% and a variable HELOC at an example 8.50%. Get real quotes for both before running your own version.

The blended rate is total interest divided by total debt: $19,544 / $257,500 = 7.59%.

Now compare that with what the property earns on the same dollars. The example house produces net operating income of $17,856 a year, worked out in the next section. Against the all-in cost of $257,500, that is a 6.93% yield.

The property earns 6.93% on money that costs 7.59%. The gap is negative, and it has a dollar value: $19,544 of interest minus $17,856 of NOI is a $1,688 shortfall before a single dollar of principal is paid. Every dollar of principal on either loan comes out of your paycheck on top of that.

This is the test most HELOC plans skip. When you put your own cash down, a thin spread between yield and borrowing cost still leaves positive cash flow, because a quarter of the purchase has no interest bill. When the down payment is borrowed too, there is no free layer. The property yield has to beat the blended rate by enough to cover principal, or the deal runs on your salary.

What the rental must earn to carry both payments

Here is the full monthly picture for the example house. It rents for $2,400, which is a 0.96% monthly rent-to-price ratio, better than many markets offer.

Annual NOI is $1,488 x 12 = $17,856. The first mortgage payment is $187,500 at 7.25% over 360 months. The HELOC payment is $70,000 x 8.50% / 12 = $496, and it buys no principal reduction at all.

Interest-only is also the friendly case. Many lines run a draw period, commonly 10 years, followed by a repayment period, commonly 20. At the same example 8.50% rate, the amortizing payment on $70,000 over 20 years is $607. Cash flow with that payment is -$398 a month.

The rent-to-price ratio that carries both loans

Solve for the rent instead of hoping. In this pro forma, vacancy, management and reserves scale with rent and take 22.6% of it (5% plus 7.6% plus 10%). Taxes and insurance are fixed at $370. So rent x 0.774, minus $370, has to equal the debt payments.

Check the middle row: $2,771 x 0.774 = $2,145, minus $370 is $1,775. It ties.

A conventional buyer needs a 0.85% ratio to break even on this house. The HELOC buyer needs 1.11% to break even while paying interest only, and 1.17% once the line amortizes. Those are break-even figures with nothing left over. Add a $100 monthly cushion and the amortizing case needs $3,044 of rent, a 1.22% ratio.

Houses that rent for 1.2% of their price every month exist, mostly at lower price points with older systems and heavier management. They are not what most people picture when they plan to borrow against a home to buy a rental across town. If your market delivers 0.7% to 0.9%, the HELOC down payment produces a negative-carry rental, and you should call it that in your plan.

HELOC on your primary vs on another rental

The line can sit on either kind of property. The terms differ enough to matter.

Do not rely on any specific loan-to-value cap from an article. Lenders set their own and change them, so ask three of them and write the answers down.

The primary residence line is cheaper and easier to get, which is why most people use it. It is also the version where a bad rental can cost you your home. A failed tenant, a roof and a rate reset can arrive in the same year, and the HELOC lender's lien does not care which property caused the shortfall.

A line on an existing rental keeps the risk inside the investment portfolio. You pay for that with a higher rate and a smaller line. For an investor with two or three paid-down rentals, that trade is usually worth it. The cost difference on a $70,000 draw at one extra point is $700 a year, which is cheap insurance for keeping your residence out of the structure.

One tax point, briefly. Interest on a HELOC is generally treated according to how the borrowed money was used, not which house secures it. Money traced to buying a rental generally belongs with that rental's expenses instead of your home mortgage interest deduction. Keep the draw in a clean paper trail and have a CPA confirm the treatment.

The risks: variable rates, frozen lines, and 2008's lesson

The rate moves. HELOCs float with an index, usually the prime rate, plus a margin. Here is the example deal at three rates.

Each point of rate costs $58 a month on a $70,000 balance. The rent does not rise when the index does.

The line can be frozen or cut. A HELOC is a revocable commitment. In 2008 and 2009, as home values fell, lenders froze lines and reduced limits on borrowers who had never missed a payment. Anyone who planned to use the undrawn portion as a reserve fund found out it was gone at the moment they needed it. The lesson still holds: an undrawn HELOC is not an emergency fund. If the same line is both your down payment and your safety net, you have no safety net.

The payment steps up. When the draw period ends, the payment converts from interest-only to amortizing. In the example that is $496 to $607 at an unchanged rate. If rates are higher by then, both effects stack.

Two properties share one failure. A conventional rental that goes bad can be sold, and the loss stops at your down payment. Here the down payment is a lien on your residence. Selling the rental at a loss leaves HELOC debt behind, secured by your home, with no asset attached to it.

The payoff comes from wages. The rental in the example cannot retire the line. Paying off $70,000 in 5 years takes $1,167 a month of principal from outside the deal. Seen plainly, this strategy is buying a down payment on an installment plan. That can be a reasonable plan for someone with strong income and no patience for saving. It is a poor plan for someone who needs the rental to pay for itself.

The go and no-go numbers

Run these before you draw on the line.

1. Count both payments. Cash flow must be positive with the first mortgage and the HELOC at its amortizing payment, not the interest-only teaser.
2. Shock the rate. Add 2 points to the HELOC rate and rerun it. If the deal only works at the opening rate, it does not work.
3. Compare yield with blended cost. NOI divided by total cost should exceed the blended rate on all debt. In the example it was 6.93% against 7.59%, which is a no.
4. Write the payoff schedule. Name the monthly principal amount and where it comes from. A refinance of the rental is a payoff source only if the value will be there, so treat it as a bonus.
5. Hold reserves outside the line. Six months of both payments plus operating costs, in cash. The unused HELOC does not count.
6. Know the break-even ratio. At these example terms it takes a rent-to-price ratio near 1.2%. Your terms will differ, so compute yours.

A go looks like this: the rent carries both amortizing payments with room to spare at a stressed rate, your income can retire the line in 3 to 5 years, and your cash reserves are intact. A no-go is anything where the first positive number on the spreadsheet appears only after you delete the HELOC row.

The practical step is to model it the way the bank account will feel it. In the single family calculator, enter the first mortgage as the loan and add the HELOC payment as a second debt line instead of leaving it off the page. If the deal still cash flows with that line included, the strategy is real and not hope. If it goes negative, you now know the monthly price of buying with no money down, and you can decide whether that price is worth paying.