Buying a house when you already own a house comes down to three moves: unlock the equity in your current home to fund the next down payment, write the new offer so you are not trapped if your sale falls through, and time the two closings so you are not paying two mortgages any longer than necessary. Most homeowners use some combination of short-term financing, contingency clauses, and coordinated closing dates to make it work.
Start With the Equity You Actually Have
The first number you need is your usable equity. Take your home’s current market value, subtract what you still owe on the mortgage, then subtract what selling will cost you. A real estate agent’s comparative market analysis is usually free; a formal appraisal runs roughly $300 to $425. Selling costs typically include agent commissions (historically 5% to 6% of the sale price, though increasingly negotiable) plus closing costs of about 1% to 2%. What’s left is the cash that can realistically go toward the next house.
Equity is only half the picture. Your lender will also look at your debt-to-income ratio, comparing all of your monthly debt payments — including both mortgages if you’ll briefly carry two — against your gross monthly income. Fannie Mae sets the baseline at 36% for manually underwritten conventional loans, allows up to 45% with strong credit and reserves, and permits up to 50% on loans run through its automated underwriting system.1Fannie Mae. B3-6-02, Debt-to-Income Ratios That ceiling effectively caps the price of the new home while your current mortgage is still in the picture.
How to Fund the New Purchase Before the Old House Sells
Your equity is real, but it’s locked up until closing day on the sale. Several products can free some of it up early, each with different costs and risks.
Bridge Loans
A bridge loan is short-term financing built for exactly this situation. Terms usually run six months to a year, with rates roughly 2% to 3% above standard mortgage rates. Payments are often interest-only, with a balloon payment covering the full principal when your current home sells or the loan term ends.2Chase. Bridge Loans: Everything You Need to Know If the sale drags, that balloon payment can come due before you have the proceeds to cover it.
Home Equity Line of Credit
A HELOC lets you draw against your current home’s equity as a revolving line, paying interest only on what you actually borrow. Qualification hinges on your loan-to-value ratio; some lenders require you to keep at least 20% equity in the home, while others allow borrowing against a larger share. A HELOC takes time to set up, so opening one before you start seriously house-hunting is worth doing.
401(k) Loan
If your employer’s plan permits it, you can borrow the lesser of $50,000 or 50% of your vested balance. Some plans let you borrow up to $10,000 if 50% of your balance is less than that. Loans used to buy a primary residence are exempt from the standard five-year repayment window, so the timeline is more flexible.3Internal Revenue Service. Retirement Topics – Loans The trade-off: the borrowed money isn’t invested, and if you leave your job, the full balance may be due on a compressed timeline.
Writing an Offer When You Still Own a House
Your offer needs language that protects you if your current home doesn’t sell as planned. These are contingencies, and they let you walk away and keep your earnest money — usually 1% to 3% of the purchase price — if certain conditions aren’t met.
Sale of Home Contingency
This gives you a defined window, often 30 to 60 days, to get your current home under contract. Miss the window and you can withdraw with your earnest money intact. Sellers commonly ask for proof that your home is actively listed, often a copy of the MLS listing.
Settlement Contingency
If your current home is already under contract, a settlement contingency ties the new purchase to that sale actually closing. It’s a stronger position than a sale contingency because a committed buyer is already in place. Spell out the expected closing date and what happens if it slips.
Kick-Out Clause
Sellers who accept a contingent offer often insist on a kick-out clause. It lets them keep marketing the property, and if a competing offer comes in, you get a set window (typically 72 hours) to either drop your contingency and commit or step aside.
Making a Contingent Offer Competitive
In a tight market, a home sale contingency weakens your offer. Ways to push back: get your current home under contract before making the offer, put down a larger earnest money deposit, shorten the contingency window, or drop the contingency entirely and rely on bridge financing to cover the gap. That last approach is riskier for you but far more attractive to a seller.
Coordinating the Two Closings
The ideal is a back-to-back closing: sell in the morning, buy in the afternoon, with the escrow officer directing your sale proceeds straight into the new down payment. Done right, you never carry two homes and never need temporary housing. Done wrong, a delay on either side cascades into the other transaction. It takes tight coordination between both buyers, both sellers, both lenders, and the title companies.
Wet Funding Versus Dry Funding
How quickly you get keys after signing depends on your state. In wet funding states, which cover most of the country, the lender releases funds immediately at signing and you take possession the same day. In dry funding states — Arizona, California, Nevada, Oregon, Washington, and a few others — the lender holds funds until all paperwork is verified, which can add days between signing and possession. Build that gap into a same-day closing plan.
Rent-Back Agreements
If the dates don’t line up, a rent-back agreement lets you stay in your old home for a short period after selling it. Most lenders cap rent-backs at 59 days or fewer, because longer occupancy can conflict with the new owner’s owner-occupancy loan requirements. Under 30 days is usually handled as an addendum to the purchase contract; longer stays may require a separate lease with landlord-tenant obligations.
Rent is commonly set at the new owner’s daily carrying cost — the mortgage, taxes, and insurance divided by 30 — though the parties can negotiate freely. Some buyers offer a free rent-back as a concession. If you’re the one who will need to stay, negotiate the rent-back terms while you’re negotiating price.
What It Costs If Your Old Home Doesn’t Sell
The core financial risk is straightforward: your current home lingers on the market and you end up paying two mortgages, two tax bills, and two insurance policies at once. Even a two-month overlap can run into thousands of dollars. Before committing to a purchase, stress-test your budget against three to six months of double payments funded from income alone.
In a slow market, the safer move may be to flip the sequence: list first, get your current home under contract, then make your offer. You may need temporary housing between closings, but you eliminate the open-ended risk of carrying both properties. Pricing your current home aggressively enough to sell quickly, even at a modest discount, can save more than months of double payments would cost.
Two Tax Rules Worth Checking Before You List
If you sell your primary residence at a profit, you can exclude up to $250,000 of the gain from taxable income ($500,000 on a joint return). To qualify, you must have owned and lived in the home as your primary residence for at least two of the five years before the sale. The two years don’t need to be consecutive, but both the ownership and use tests have to be met inside that five-year window, and you can’t have claimed the exclusion on another home sale in the two years before this one.4Office of the Law Revision Counsel. 26 USC 121 – Exclusion of Gain From Sale of Principal Residence If you’re close to the two-year mark, waiting a few weeks to list can be worth thousands.
On the mortgage interest side, for loans taken out after December 15, 2017, the deduction applies to the first $750,000 of combined mortgage debt ($375,000 if married filing separately). When you briefly carry two mortgages during the transition, interest on both counts toward the combined cap. Older mortgages remain under the prior $1 million limit.5Internal Revenue Service. Publication 936, Home Mortgage Interest Deduction