Renting Out Your House to Buy Another Home

The plan sounds almost too good. You bought in 2020 at 3%, the house has gained six figures in value, and instead of selling it to fund the next place, you keep it, rent it out, and let a tenant pay down a cheap mortgage while you move on. Two properties, one of them essentially free money.

Sometimes it really is that good. Often there's a catch buried in the financing or the tax code that nobody mentions until it's expensive. Here's what actually decides whether this works.

Can you even get the next mortgage?

This is the question people skip, and it's the one that sinks the plan most often. When you apply for the loan on your new home, the lender still sees the mortgage on the old one. Two mortgages, one income. Your debt-to-income ratio has to survive that math.

There's a partial rescue: lenders will usually count expected rent from the departing home as income — but not all of it, and not always without a fight. The common rule is 75% of the market rent, the missing 25% being their assumption about vacancy and repairs. So if the place rents for $2,000, the lender might credit you $1,500 against the $1,400 mortgage payment on it. That small positive is often the difference between qualifying and not.

The friction is in the proof. Many lenders want a signed lease, and some want the first month's rent already deposited, before they'll count a dollar of it. Others require you to hold reserves — several months of payments on both homes sitting in the bank. If you're stretching to make the new purchase work, find out your lender's exact rule before you fall in love with a listing. It changes what you can afford.

The low rate is the real asset

Strip away the sentimental stuff and a 3% mortgage is a financial instrument you will probably never be issued again. Money was briefly on sale and you locked some in.

That single fact reframes the decision. A rental that only breaks even on cash flow can still be worth keeping purely to hold onto the loan, because every month a tenant covers the payment, you're retiring principal at an interest cost that's below inflation. Sell, and that advantage is gone for good — the next investment property you buy comes with today's investor rate, which runs a point or so above owner-occupied. People fixate on the monthly cash flow and miss that the cheap debt is often worth more than the rent.

The tax clock you start the day you move out

Now the part that quietly costs people the most.

While a home is your primary residence, the IRS hands you an enormous gift: live there two of the last five years and you can exclude up to $250,000 of gain from tax when you sell — $500,000 if you're married and file jointly. For a house that's appreciated a lot, that exclusion can be worth tens of thousands of dollars.

The catch is the word "last." That five-year window keeps moving. Rent the house out and the clock keeps ticking; once you've been gone more than three years, you've blown past the two-of-five test and the exclusion is gone. There's no partial credit for "I lived there a long time before renting it." You either meet the test or you don't.

So renting isn't free even when the tenant covers everything. If your house has a large unrealized gain, holding it past that three-year mark can convert a tax-free sale into a taxable one — and you'll also owe depreciation recapture on top, since you're required to depreciate the property once it's a rental whether you claim it or not. Sometimes the smartest move is to rent for a year or two, then sell while the exclusion is still alive.

Run the actual numbers

Say the house is worth $450,000, you owe $220,000 at 3.1%, and it rents for $2,600 a month. The mortgage runs about $1,250; add taxes, insurance, and a realistic maintenance and vacancy allowance and you're clearing maybe $300 a month after everything. Not nothing, not life-changing.

The case for keeping isn't that $300. It's the $220,000 loan at 3.1% you'd never replace, plus a tenant knocking down the principal, plus appreciation on a $450,000 asset instead of on the smaller pile of cash you'd net from selling. The case for selling is the tax-free gain sitting in the house right now, the hassle you avoid, and the freedom to put that equity somewhere you actually understand.

Which one wins depends on your numbers and your holding period, and it's genuinely close more often than people expect. Put both paths side by side in the keep-vs-sell calculator before you decide — the tax clock alone can flip the answer.

When keeping usually makes sense

• The loan is well below current rates and the payment is covered by rent
• You'd clear the two-of-five exclusion by selling soon or the gain is small enough that tax isn't a factor
• The rental market where you're leaving is strong, with low vacancy
• You can qualify for the new mortgage without draining your reserves
• You actually want to be a landlord, or you'll happily pay someone 8–10% to be one for you

When selling is the better call

• Your gain is large and you're near the three-year cliff on the exclusion
• Cash flow is clearly negative once you count vacancy, repairs, and management honestly
• You need the equity to make the next purchase work at all
• The idea of a 1 a.m. repair call from four states away makes you want to lie down

Frequently asked questions

Can I use the rent to qualify for my new mortgage?

Usually yes, but expect the lender to count only about 75% of the market rent and to ask for proof — often a signed lease, sometimes a deposited first month's rent. Some lenders also require cash reserves covering both mortgages. Confirm the exact requirement before you shop.

Do I lose my low mortgage rate if I rent the house out?

No. Renting doesn't change your existing loan or its rate. What you give up is the ability to replace that rate — sell, and any future investment property comes with today's higher investor rates.

How long can I rent my old home before I lose the capital gains exclusion?

The exclusion requires you to have lived there two of the five years before the sale. Rent it out for more than three years and you no longer meet that test, and the exclusion disappears. Time the sale if the tax break is worth a lot to you.

Is it better to rent or sell if my house has gone up a lot in value?

A large gain pushes toward selling while the tax-free exclusion still applies, unless the property cash-flows strongly and you plan to hold for many years. Run both paths — the tax difference is often larger than a couple of years of rent.