If you’re buying a house with a partner and you’re not married, the protections that come automatically with marriage — property division rules, inheritance defaults, spousal creditor shields — don’t apply to you. You have to build that framework yourself before closing. That means choosing the deed structure deliberately, signing a written co-ownership agreement, understanding that both names on the mortgage means both of you owe the whole loan, and planning now for what happens if one of you leaves, stops paying, or dies.
Most disputes between unmarried co-buyers trace back to decisions that were never made in writing. The fixes are not expensive or complicated, but they have to happen before you sign.
How to Hold Title
The way your names appear on the deed decides what happens if a co-owner dies, wants out, or gets sued. Unmarried buyers generally choose between two forms.
Joint Tenancy With Right of Survivorship
Joint tenancy gives both owners an equal share and includes a right of survivorship. If one owner dies, the other automatically inherits the deceased owner’s share without probate, regardless of what any will says. For partners who want the survivor to keep the home no questions asked, this does the job cleanly.
The catch is rigidity. Joint tenants must hold equal shares. Contribute 70% of the down payment while your partner contributes 30%, and the deed still reads 50/50. You can correct that imbalance in a separate co-ownership agreement, but the deed itself won’t reflect it.
Tenancy in Common
Tenancy in common lets each owner hold a distinct percentage that can track actual contributions. There is no survivorship. When a co-owner dies, that share passes through their estate under their will, or under state intestacy rules if there is no will, which typically routes assets to parents or siblings rather than an unmarried partner. If you choose this structure, each partner needs a will or trust that specifically addresses the ownership share.
One Option You Don’t Have
Tenancy by the entirety, a form of co-ownership that shields the property from one owner’s individual creditors, is available only to married couples in the states that recognize it. Unmarried partners cannot use it. That is one more reason the written agreement below matters.
Both Names on the Mortgage Means Both of You Owe All of It
This is where co-buyers get blindsided. Whatever your co-ownership agreement says about splitting payments, the lender is not a party to it. When both partners sign the promissory note, each becomes personally liable for the entire loan balance under what’s called joint and several liability. The lender can pursue either signer for 100% of the debt.
If your partner stops paying their share, you either cover the shortfall or the loan goes into default. A default hits both credit scores, because the delinquency is reported against every name on the note. An agreement that says “each partner pays half” is enforceable between the two of you. It means nothing to the bank.
Before signing, have a direct conversation about what happens if one of you loses a job, gets sick, or simply stops contributing. Building a reserve of at least three months of mortgage payments is one of the most practical protections you can put in place. The written agreement should spell out how long the paying partner covers a shortfall, whether that shifts ownership shares, and when nonpayment triggers a forced sale.
The Co-Ownership Agreement
A co-ownership agreement is a private contract between you and your partner covering how you share the property. It sits alongside the deed and mortgage, and it is the single most important document for protecting yourself. Without one, general state property law fills the gaps, and it rarely fills them in a way either of you would have chosen.
Money
Document exactly what each partner contributed to the down payment, closing costs, and any pre-purchase renovations. Specify how ongoing costs will be split: mortgage payments, property taxes, insurance, repairs, utilities. The split can be equal, proportional to income, or proportional to ownership share. It just has to be explicit.
Decisions
Set a dollar threshold above which both partners must agree before spending. Small repairs shouldn’t require a committee; a major renovation should. Include how you’ll handle refinancing, renting out a room, or taking on a home equity loan.
Exits
The exit provisions are the part people skip and later regret. Address what happens if one partner wants to sell, if the relationship ends, and how a buyout will be valued. Common methods include a professional appraisal or the average of two independent appraisals. Factor the appraisal cost into the agreement.
Include a right of first refusal, giving the remaining partner the first opportunity to buy the departing partner’s share before it goes to an outside buyer. Without it, your co-owner could sell their share to anyone, and you could find yourself sharing a home with a stranger or an investor. Specify how long the remaining partner has to exercise the right and how the price gets set.
Dispute Resolution
Require mediation or arbitration before either partner can sue. Litigation over co-owned property is slow and expensive, and it eats whatever equity is in the house. Mediation is cheaper, faster, and private; arbitration provides a binding resolution without a full trial.
Keep a Paper Trail From Day One
Documentation prevents arguments. From the first check you write toward the down payment, save receipts, bank statements, and transfer confirmations. A shared spreadsheet tracking contributions, updated monthly, takes little effort and pays for itself the first time a disagreement comes up.
For ongoing costs, open a joint bank account used only for the property. Each partner deposits their share on a set schedule, and all mortgage, tax, insurance, and repair payments come out of that account. Keep personal expenses out of it. When one partner contributes significantly more to a major improvement like a roof or an addition, document that separately and consider updating the agreement to reflect the added investment. Proving three years later that you paid for a renovation becomes a credibility contest without records.
Tax Rules That Treat You Differently
Married couples get several tax advantages unmarried co-owners do not. Knowing where the code diverges lets you plan around it.
Capital Gains When You Sell
If you’ve lived in the home as your primary residence for at least two of the five years before selling, federal law lets you exclude up to $250,000 of profit from taxable income. Each qualifying unmarried co-owner can claim this exclusion independently, so a couple selling a jointly owned home could potentially exclude up to $500,000 combined, matching what married couples filing jointly receive. The exclusion can be claimed once every two years.
Gift Tax
Gift tax catches unmarried co-buyers off guard more than any other issue. If both names go on the deed but one partner paid the entire down payment, the IRS may treat the nonpaying partner’s ownership share as a gift. Adding someone to a deed for no financial consideration is treated as a gift of their share of the property’s fair market value.
In 2026, the federal annual gift tax exclusion is $19,000 per recipient. If the gifted share exceeds $19,000, the giving partner must file IRS Form 709 even if no tax is ultimately owed, and the excess reduces the donor’s lifetime estate and gift tax exemption. That lifetime exemption matters more in 2026 than it did recently: following the expiration of the Tax Cuts and Jobs Act provisions, it has reverted from roughly $13 million to approximately $5 million adjusted for inflation. Partners making large unequal contributions should talk to a tax professional before closing.
Mortgage Interest Deduction
Unmarried co-owners who itemize can each deduct the mortgage interest they actually paid during the year. If you split the mortgage 50/50, each partner deducts half. If one partner pays 70%, that partner deducts 70%. Only the partner whose Social Security number is on the Form 1098 from the lender receives that form, so the other partner needs independent records to support the deduction.
If the Relationship Ends
With a co-ownership agreement in place, you follow it. One partner buys the other out at the agreed valuation, or you sell and split the proceeds according to your ownership shares.
Without an agreement, you are in a weaker position. Unmarried partners have no legal right to financial support from each other, and general property law defaults are blunt. The person whose name is on the title and who can prove they paid holds the stronger hand. If both names are on the deed and you can’t agree, your remaining option is a partition action.
A partition action is a lawsuit asking a court to force the sale or division of co-owned property. Any co-owner can file. For a house, courts almost always order a sale rather than a physical split, because you can’t meaningfully divide a home. The property is sold, often below market because of the forced-sale circumstances, and proceeds are divided based on ownership shares after legal fees and court costs come out. Most jurisdictions first require the departing owner to offer the other partner a chance to buy the share at fair market value. Partition suits are slow, expensive, and almost always leave both sides worse off than a negotiated resolution would have.
If a Partner Dies
The deed structure controls what happens to the ownership share. Joint tenancy sends it automatically to the survivor. Tenancy in common sends it to the deceased partner’s estate under a will or state intestacy law.
Either way, the survivor still owes the full mortgage payment. The lender does not pause collections because a co-borrower died. This is where term life insurance becomes a practical necessity: a policy on each partner, with the co-owner named as beneficiary, can provide enough to pay down or pay off the loan if the worst happens. For a healthy person in their 30s or 40s, term coverage is inexpensive compared to the risk of losing the home.
If you hold the property as tenants in common, make sure your will explicitly addresses your ownership share. Intestacy rules typically send assets to parents, siblings, or other relatives — not to an unmarried partner.
Use an Attorney
A co-ownership agreement doesn’t require the most expensive lawyer in town, but it does require one. Template agreements pulled off the internet miss state-specific requirements and don’t account for your finances. A real estate attorney can draft the agreement, review the deed structure, and flag tax issues for a few hundred to a couple thousand dollars depending on complexity and location. That fee is small next to the price of the house and much smaller than the cost of a dispute.
Ideally, each partner has a separate attorney review the agreement. At minimum, each partner should have the chance to get independent legal advice before signing. An agreement one partner drafted and the other signed without review is harder to enforce if it is ever challenged.