A co-owner is any person who shares legal title to an asset with at least one other person. In real estate, the form of co-ownership written into the deed decides the questions that matter most: whether your share passes to your heirs or automatically to the other owners when you die, whether a creditor can reach the property for another owner’s debts, how income and expenses get split, and how you get out if the arrangement stops working. Four main structures exist under U.S. law, and the differences between them are not academic.
The Four Forms of Co-Ownership
Tenancy in Common
Tenancy in common is the default in most places. If a deed names multiple owners without specifying a different arrangement, the law usually presumes a tenancy in common. Each owner holds a separate, undivided interest, meaning everyone can use the whole property even though nobody owns a specific physical portion of it.
Shares do not have to be equal. One person might hold 70% while two others split the remaining 30%. Each owner can sell, gift, or mortgage their share without the others’ permission, and each can leave their share to anyone they choose in a will. There is no right of survivorship: when a tenant in common dies, their interest passes through their estate to their heirs or named beneficiaries, not to the surviving co-owners. A new co-owner who buys or inherits a share may be a complete stranger to the others.
Joint Tenancy With Right of Survivorship
Joint tenancy ties co-owners together more tightly. Every joint tenant holds an equal, undivided interest, and when one owner dies, that person’s share automatically passes to the surviving joint tenants rather than going through probate or following a will. That right of survivorship is the reason most people choose joint tenancy.
Creating a valid joint tenancy requires four conditions, traditionally called the “four unities.” Each owner must receive their interest at the same time, through the same document, in equal shares, and with equal rights to possess the whole property.1Legal Information Institute. Joint Tenancy If any of those conditions breaks, the joint tenancy converts into a tenancy in common. This happens most often when one joint tenant sells or transfers their share. The transaction destroys the unities of time and title, and the new owner holds their interest as a tenant in common while the remaining original owners stay joint tenants with each other.
One detail that surprises people: a joint tenant can sever the arrangement unilaterally. No one needs to agree. A single conveyance to a third party is enough. If you’re relying on survivorship as part of your estate plan, understand that any co-owner can eliminate it at any time without telling you.
Tenancy by the Entirety
Tenancy by the entirety is available only to married couples and is recognized in most states, though a handful also extend it to domestic partners.2Legal Information Institute. Tenancy by the Entirety It works like joint tenancy in one crucial respect: when one spouse dies, the survivor automatically receives full ownership. But it adds a layer of protection joint tenancy lacks.
Neither spouse can sell, mortgage, or transfer the property without the other’s consent. That mutual-consent requirement also shields the property from creditors with a claim against only one spouse. If your spouse owes money on a credit card or gets sued personally, a creditor generally cannot force the sale of property held as tenants by the entirety to satisfy that debt. The protection has limits. Federal tax liens are a notable exception; the U.S. Supreme Court held in United States v. Craft (2002) that the IRS can attach a lien to entirety property even when only one spouse owes the tax debt. Joint debts that both spouses share can also reach the property.
Community Property
Nine states use a community property system: Arizona, California, Idaho, Louisiana, Nevada, New Mexico, Texas, Washington, and Wisconsin. In these states, most assets that either spouse earns or acquires during the marriage belong equally to both spouses, regardless of whose name is on the title or who earned the income.3Internal Revenue Service. IRM 25.18.1 – Basic Principles of Community Property Law
Property owned before marriage, along with gifts and inheritances received by one spouse alone, typically stays separate. Separate property can turn into community property if it gets mixed with marital funds or if both spouses contribute to it over time. At divorce, community property states start from a presumption of equal division, but not all enforce a strict 50/50 split. Some allow judges to divide property in whatever way they consider fair, which can produce unequal results.
What Every Co-Owner Can Do
Regardless of form, every co-owner has the right to use and occupy the entire property. A co-owner holding a 20% interest can walk through the same front door and use the same rooms as the co-owner holding 80%. No one can lock out another co-owner or restrict them to a certain part of the property. If a co-owner is physically excluded (locks changed, entry refused), that’s called an ouster, and the excluded owner can go to court to regain access and recover damages measured as their proportionate share of the property’s fair rental value for the period they were shut out.
When co-owned property generates rental income, each owner is entitled to their proportionate share. A tenant in common with a 40% interest gets 40% of the rent; joint tenants split equally. The same proportional logic applies to costs: property taxes, insurance, mortgage payments, and necessary maintenance. When one co-owner covers more than their share of necessary expenses, they can typically seek reimbursement from the others, though enforcing that right often requires legal action.
Improvements are the trickier category. If you renovate a shared property without the other owners’ agreement, you cannot simply send them a bill. Courts distinguish between necessary repairs that preserve the property and voluntary improvements that enhance it. For necessary repairs, co-owners generally owe contribution. For improvements like a kitchen remodel or a new deck, you’re in weaker territory. In a partition proceeding, a court may credit you for the increase in property value your improvements created, but the credit is typically capped at either the cost you spent or the value actually added, whichever is lower. Outside of partition, some courts have held that co-owners have no right to reimbursement for improvements absent an agreement.
Mortgage Liability When Co-Owners Borrow Together
When co-owners take out a mortgage together, each person who signs the loan is fully liable for the entire balance, not just their ownership share. If one co-owner stops paying, the lender doesn’t care about your internal agreement. The other borrowers must cover the shortfall or face foreclosure and credit damage that hits everyone on the loan. Late and missed payments show up on every borrower’s credit report equally.
The co-owner who keeps paying to protect the property can seek reimbursement from the one who stopped, but collecting on that claim is a separate fight. An agreement that specifies consequences for missed payments, including triggering a mandatory buyout, goes a long way toward preventing this from spiraling.
Tax Rules Co-Owners Should Know
Rental Income
Each co-owner reports their proportionate share of rental income on their own return. Married couples who jointly own rental property are generally treated as a partnership for federal tax purposes, but they can elect to file as a “qualified joint venture” if both spouses materially participate in managing the property and they file a joint return.4Internal Revenue Service. Election for Married Couples Unincorporated Businesses That election lets each spouse report their share on a separate Schedule C rather than filing a partnership return. Unmarried co-owners with a rental property may need to file a partnership return (Form 1065), depending on the level of shared business activity.
Gift Tax on Transfers
Adding someone to a property title or selling them a share below fair market value can trigger federal gift tax rules. For 2026, you can give up to $19,000 per recipient per year without owing gift tax or filing a return.5Internal Revenue Service. Frequently Asked Questions on Gift Taxes Married couples who elect gift-splitting can combine their exclusions to give up to $38,000 per recipient.6Internal Revenue Service. Rev. Proc. 2025-32 Transfers exceeding those thresholds require a gift tax return (Form 709), and the excess reduces your lifetime estate and gift tax exemption.
Basis Step-Up at Death
How co-ownership is structured can produce very different tax results when one owner dies. Under federal tax law, property acquired from a decedent generally receives a new tax basis equal to its fair market value at the date of death.7Office of the Law Revision Counsel. 26 USC 1014 – Basis of Property Acquired From a Decedent For joint tenancy between non-spouses, only the deceased owner’s share gets stepped up. If you and a friend each own 50% as joint tenants and your friend dies, only their half receives the new basis; your half keeps its original basis. Community property gets a better result: when one spouse dies, the entire property (both halves) can receive a stepped-up basis, potentially eliminating a large capital gains tax bill if the survivor later sells.
1031 Exchanges and Tenancy in Common
Investors who sell real property can defer capital gains tax by reinvesting in like-kind replacement property through a Section 1031 exchange. The replacement property must be identified within 45 days of the sale and acquired within 180 days.8Office of the Law Revision Counsel. 26 USC 1031 – Exchange of Real Property Held for Productive Use or Investment Interests in partnerships and LLCs do not qualify as real property for this purpose, which is why some investment sponsors structure shared ownership as a tenancy in common. A TIC interest counts as direct real property ownership, preserving the tax deferral that would be lost if the same property were held through an entity.
How Co-Ownership Gets Created
The most common path is a property deed that names multiple people as owners. The specific language in the deed determines the form. A deed that simply lists two names without further detail usually creates a tenancy in common by default. Creating a joint tenancy or tenancy by the entirety requires explicit language, something like “as joint tenants with right of survivorship” or “as tenants by the entirety.”
Co-ownership can also arise without anyone planning for it. When someone dies without a will, state intestacy laws may distribute a property interest to multiple heirs, making them tenants in common whether they wanted to share ownership or not. Inherited co-ownership is one of the most common sources of partition disputes, because the co-owners may be relatives with very different ideas about what to do with the property.
How Co-Ownership Ends
Voluntary Sale or Buyout
The cleanest exit is a voluntary one. All co-owners agree to sell and split the proceeds according to their interests, or one co-owner buys out the others. A buyout requires agreement on value, which usually means an independent appraisal. If you have a co-ownership agreement with a pre-set valuation method, this step becomes much simpler.
Partition Actions
When co-owners cannot agree, any co-owner can file a partition action asking a court to force a resolution. Courts can order two kinds. A partition in kind physically divides the property into separate parcels, which works for large tracts of land but is impractical for a single house. More commonly, the court orders a partition by sale: the property is sold and the proceeds divided among the owners according to their interests, with credits and offsets for unequal contributions to expenses or improvements.
Partition actions are expensive. Court filing fees alone typically run several hundred dollars, and attorney fees can push total costs well into the thousands. Court-ordered sales also tend to produce below-market prices because they lack the negotiating leverage of a voluntary listing. Mediation is cheaper, faster, and more likely to produce a price everyone can live with.
Death of a Co-Owner
What happens next depends entirely on the form of ownership. In a joint tenancy or tenancy by the entirety, the right of survivorship means the deceased owner’s interest passes automatically to the surviving owners. There’s no probate, no will interpretation, and no delay; the transfer happens by operation of law the moment the co-owner dies. In a tenancy in common, the deceased owner’s share goes to their estate and is distributed according to their will or state intestacy laws. The surviving co-owners have no automatic claim to that share and may end up sharing the property with the deceased owner’s heirs.
Why a Written Co-Ownership Agreement Matters
The law fills in gaps when co-owners don’t have a written agreement, but it fills them in with default rules that may not match what you actually want. A co-ownership agreement lets you set the terms before a dispute forces a judge to do it. At minimum, a useful agreement addresses:
- Expense allocation: who pays what share of the mortgage, taxes, insurance, and maintenance, and what happens if someone falls behind.
- Use and occupancy: whether all owners will live in the property, whether it will be rented, and how decisions about use get made.
- Right of first refusal: whether the remaining owners get the chance to buy a departing owner’s share before it goes to an outsider, and on what timeline.
- Buyout terms: how the property will be valued for a buyout (independent appraisal, agreed formula, or another method) and how payment will work.
- Dispute resolution: whether disagreements go to mediation or arbitration before anyone files a lawsuit.
- Exit triggers: what events allow or require a sale, including death, divorce, bankruptcy, or one owner simply wanting out.
Without these terms in writing, every disagreement becomes a negotiation from scratch, and the fallback is a partition action nobody wants.