TL;DR

• Unmarried couples who buy a home together have none of the marital protections that govern property when a married couple divorces — no community property, no divorce framework to divide the home.
• By default they own as tenants in common, and at a breakup either partner can generally force a sale through partition.
• Unequal down payments, unequal mortgage contributions, and verbal “we’ll sort it out” understandings are where these situations go wrong.
• A written property/co-ownership agreement signed before or at purchase is the single best protection — defining shares, contributions, buyout rights, and what happens at a split or a death.
• Without one, a breakup can become a property lawsuit; with one, it is a defined process.

Buying together without the safety net

When a married couple divorces, an entire body of law governs how their home is divided. When an unmarried couple splits up, that safety net does not exist. There is no community property, no marital estate, no family-court framework to divide the home fairly — there is only how the title is held and whatever the couple did or didn’t agree to in advance. That gap surprises many couples, who assume that buying a home together creates some built-in fairness. It does not. For unmarried partners, the protections you have are almost entirely the ones you create for yourselves, ideally before you buy.

This guide covers what unmarried couples should do before buying together, and what happens — and what your options are — if the relationship ends.

How unmarried couples usually own (and why it matters)

Unless they arrange otherwise, unmarried co-owners in California typically hold title as tenants in common, each owning a share of the property. (Some choose joint tenancy for its right of survivorship, which carries its own consequences covered elsewhere in this series.) Tenancy in common has two features that matter enormously at a breakup:

• Either owner can generally seek partition. If the relationship ends and the partners can’t agree on what to do with the home, either one can ask a court to force a sale or division — the same partition right that governs any co-ownership.
• Shares are not automatically “fair.” The default assumption may not match what actually happened — who paid the down payment, who paid the mortgage, who funded the renovation. Without documentation, sorting out each partner’s true share at a breakup can become a contentious, fact-intensive fight.

This is why the absence of an agreement is so dangerous for unmarried couples specifically: they have neither the marital framework nor, usually, a written understanding to fall back on.

Where it goes wrong: contributions and assumptions

The most common flashpoints in an unmarried-couple home split are about money put in and promises made:

• Unequal down payment. One partner puts in most or all of the down payment, but title is taken 50/50, or vice versa — and at a breakup, the contributor wants that recognized while the other points to the title.
• Unequal ongoing contributions. One partner pays more of the mortgage, taxes, or improvements over the years, expecting it will “count” — but without documentation, proving it later is hard.
• Verbal understandings. “We agreed I’d get my down payment back first” or “we said it was 60/40” — perfectly sincere, and very difficult to enforce when memories and incentives diverge after a breakup.
• One partner not on title at all. A partner who contributed but was left off the deed may have to pursue a claim to establish any interest, which is uncertain and costly.

California law does recognize that unmarried partners can make enforceable agreements about property and finances (the principle from the well-known Marvin line of cases), but those agreements are most useful, and most enforceable, when they are clear and ideally in writing. Relying on an unwritten understanding is exactly the gap that turns a breakup into a lawsuit.

The fix: a written agreement before you buy

The single most effective protection for an unmarried couple buying a home is a written co-ownership or property agreement, signed before or at the time of purchase, that addresses:

• Each partner’s ownership share, and how it relates to their contributions.
• How the down payment and ongoing costs are treated, and whether unequal contributions are credited.
• A buyout right — if the couple splits, can one partner buy the other out, at what value, and on what timeline?
• A right of first refusal before any sale to an outsider.
• What happens at a death (since, as unmarried partners, they do not automatically inherit from each other without estate planning).
• A dispute-resolution process — mediation before litigation, for example.

An agreement like this turns the open-ended risk of co-ownership into a defined, fair process, and it is far easier to negotiate while the relationship is good than to litigate after it ends. It also pairs naturally with basic estate planning, since unmarried partners who want to provide for each other at death must do so deliberately — the law will not do it for them.

If you’ve already bought — or already split

If you bought together without an agreement, it is not too late to put one in place now, while you are still on good terms. And if the relationship has already ended and you are facing a dispute over the home, you have options short of an all-out fight: negotiating a buyout, establishing each partner’s true contributions and share, agreeing to an orderly sale, or using mediation. A partition action is available as a backstop, but it is rarely the best first move. The sooner you get advice, the more options you have.

Whether you are about to buy with a partner, already co-own without an agreement, or are navigating a breakup, we can help you protect your interest in the home. For guidance on your specific situation, call (650) 668-8000 or schedule a consultation at baylegal.com/contact.

Frequently Asked Questions

What happens to our house if my partner and I break up and we’re not married?

There is no marital framework to divide it. You own it according to how title is held — usually as tenants in common — and if you can’t agree, either partner can generally force a sale through partition. How the proceeds are split can become a contested, fact-intensive question about contributions unless you have a written agreement defining each partner’s share.

Should unmarried couples have a property agreement before buying a home?

Generally, yes — it is the single best protection. A written agreement signed before or at purchase can define ownership shares, account for unequal down payments and contributions, set a buyout right and a right of first refusal, and address what happens at a breakup or a death. It is far easier to negotiate while the relationship is good than to litigate after it ends.

I paid the down payment but we took title 50/50 — can I get it back if we split?

It depends on what you agreed and what you can document. Without a written agreement, recovering an unequal down payment can be difficult and contested. California recognizes enforceable agreements between unmarried partners about property, but they are most reliable when clear and in writing. If you are in this situation, an attorney can assess your options.

Can my unmarried partner force me to sell our home?

Generally, yes, if you co-own it and cannot agree on what to do — either co-owner can typically seek partition to force a sale or division. A written co-ownership agreement can change or limit this by setting a buyout process or other rules in advance, which is why having one matters so much for unmarried couples.

Do unmarried partners inherit each other’s share of the home automatically?

No. Unlike spouses, unmarried partners generally do not automatically inherit from each other. If you want your partner to receive your share of the home at your death, you must arrange it deliberately through estate planning (or, in some cases, how title is held). Without that, your share may pass to your relatives instead, which is another reason co-ownership and estate planning go hand in hand for unmarried couples.