How to Buy a House With a Friend: What You Need to Know Before You Sign

Co-buying is one of the smartest moves in today’s housing market. But only if you set it up right.

 

The number doesn’t work on one income. That’s not a personal failure. That’s the market.

As of early 2025, the national median home price sits above $400,000. The monthly payment on a median-priced home with a 20% down payment is nearly double what it was in 2019. Co-buying, purchasing a home with a friend or partner, is one of the most direct answers to that problem.

According to a 2025 survey by Reméo Realty, 44% of co-buyers choose this path because of affordability. The strategy works. Whether it works for you depends entirely on what you put in place before you sign.

 

Co-Buying Is a Business Partnership. Treat It Like One.

Most co-buying deals don’t fail because of bad intentions. They fail because the structure wasn’t in place before something went wrong.

Buying a $500,000 asset with another person requires the same preparation you’d bring to any deal of that size. Three assumptions consistently break these arrangements:

• “We’re friends, so we don’t need a formal agreement.” Without something in writing, there’s no defined process for what happens when one person wants to sell, loses a job, or relocates. Verbal agreements don’t hold up.
• “50/50 is simplest.” Equal splits don’t reflect reality when one person contributes 60% of the down payment. Ownership needs to mirror actual contributions.
• “We’ll figure out the exit later.” Without a pre-agreed buy-out process, one person ends up trapped in an asset they can’t exit while the other holds equity they can’t access.

 

Three Questions Every Co-Buy Needs Answered Before Closing

Before you make an offer, you and your co-buyer need to work through three areas: ownership structure, mortgage structure, and decision-making. All three need clear answers before you’re under contract.

On ownership:

• How will the title be held, and does that reflect how much each person is contributing?
• How will your share be handled if something unexpected happens to one of you?

On the mortgage:

• Will both names be on the loan?
• How will monthly costs be split, and does that split mirror each person’s ownership stake?
• What happens to the mortgage if one person’s financial situation changes?

On governance:

• Which decisions require both parties to agree?
• What’s the process if you can’t agree?
• Who’s the tie-breaker, and when does an outside mediator get called in?

These aren’t hypothetical. They’re the exact questions that end up in dispute when nobody answered them upfront. Work through them together before you’re under contract, not after.

 

What to Think Through Before You Sign

A written co-ownership agreement, what we call a real estate prenup, turns shared intent into something enforceable. Here are the areas worth working through before you get to that point.

Finances

• How are the down payment and ownership percentages split?
• How will the mortgage, taxes, insurance, and repairs be divided each month?
• What’s the plan for a cash reserve? Budget 1-2% of the property value per year for maintenance. On a $700,000 home, that’s $7,000 to $14,000 annually. Build it in from day one.

Use and access

• Who’s living in the property versus holding it as an investment?
• What are the ground rules on guests, subletting, or short-term rentals?

Exit planning

• How long do both parties plan to hold the property?
• What’s the process if one person wants out?
• What life events trigger an early exit option: job relocation, marriage, serious illness?

The exit conversation is the one most co-buyers skip. Don’t skip it. Designing the off-ramp before you finalize the entrance is what separates a solid co-buy from a messy one.

 

The Financial Stress Test You Have to Run

Before you look at a single listing, answer this one question:

Can the financially weaker partner carry this mortgage for six months if the other person’s income disappears?

Not “can you both afford this together.” Run a 30-50% income reduction scenario on each owner, independently. If the deal only works when both incomes are fully intact, the purchase price is too high, the reserves are too thin, or both.

Both parties should share credit scores, debt-to-income ratios, and the last two years of tax returns before any serious conversations begin. DTI matters because lenders qualify the loan on combined income, but monthly obligations don’t disappear when one person’s income does.

Use Pairgap’s Co-Buying Power Calculator to see your real buying range before you walk into a lender’s office.

 

Where These Deals Break Down

The failure patterns are consistent. Every one traces back to unanswered questions.

• No written agreement: One person wants out in year three, the other refuses to sell, there’s no buy-out formula, and the asset becomes a stalemate.
• Mismatched timelines: One owner relocates in year four, there’s no pre-agreed exit, and both parties end up stuck.
• Unequal contributions with no conversation about decision rights: One partner pays 70% of the mortgage but assumed a 50/50 say, and resentment compounds until the asset deteriorates.
• Income or market shocks: One person loses their job, the other can’t carry the mortgage alone, and without a clear process neither owner can get out cleanly.

 

What Experienced Co-Buyers Do Differently

They choose markets with a long view. A five-to-seven-year hold needs real demand: job access, stable or improving schools, and population growth.

They think about cash flow from day one. A property with a rentable unit, basement suite, or ADU changes the risk profile significantly. An extra $1,500 per month in rental income can absorb an income disruption that would otherwise force a sale.

And before making an offer, they make sure everything below is done, not just planned:

• Both parties have shared credit scores, DTI ratios, and two years of tax returns
• Down payment split is in writing with ownership percentage reflecting it exactly
• Monthly cost split mirrors ownership
• A cash reserve is built into the monthly budget
• Both parties have had an honest conversation about their five-year plans
• Every question about timelines, exit triggers, decision-making, and dispute resolution has a written answer

The Real Estate Prenup

That written answer lives in your real estate prenup.

It’s the document that makes everything else enforceable, and the one most co-buyers don’t think about until it’s too late. Walking in prepared, with your key decisions already worked out, is what turns it from a stressful legal process into a straightforward one.

Pairgap’s Real Estate Prenup Builder walks you through every key decision, documents what both parties agree to, and gives you a clear starting point.

 

The Bottom Line

Co-buying lets two people build equity in a market that priced them out on one income.

Most people don’t have a co-buying problem. They have a co-buying-without-a-plan problem.

Get the agreement in place before you sign. Build reserves from day one. Design the exit before you finalize the entrance.

Start with Pairgap’s Co-Buying Power Calculator to see what you can actually afford together, then lock in your real estate prenup before you make an offer.