Cohabitation laws by state vary so much that two couples living identical lives across a state line can have completely different legal rights. There is no federal law governing unmarried partners who share a home, so whether you can inherit from your partner, make medical decisions for them, or claim any share of a house you helped pay for depends on where you live and what paperwork you have signed. A handful of states still have criminal cohabitation statutes on the books, eight states plus D.C. allow common law marriage, and a smaller group offer domestic partnership or civil union registries. Everywhere else, unmarried couples are legal strangers by default.
States That Still Criminalize Cohabitation
A few states technically classify unmarried cohabitation as a criminal offense, though the laws are treated as dead letters. Mississippi’s statute is the most explicit: it prohibits unmarried men and women from living together and imposes a fine of up to $500 and up to six months in jail.1Justia. Mississippi Code 97-29-1 – Adultery and Fornication; Unlawful Cohabitation North Carolina also retains a statute penalizing cohabitation between unmarried persons.
The U.S. Supreme Court’s 2003 decision in Lawrence v. Texas severely limits enforcement. The Court struck down a Texas sodomy statute on due process grounds, holding that the government cannot criminalize private, consensual intimate conduct between adults.2Justia. Lawrence v Texas, 539 US 558 Prosecutors treat cohabitation statutes as unenforceable in light of that ruling, but they can still surface in adjacent contexts like custody disputes or morality clauses in older contracts.
States That Recognize Common Law Marriage
A common law marriage lets a couple become legally married without a license or ceremony. As of 2025, it can be established in Colorado, Iowa, Kansas, Montana, Oklahoma, South Carolina, Texas, and the District of Columbia. Rhode Island has recognized common law marriage through case law, though the state introduced legislation in 2025 (H.B. 5258) to abolish it for any new common law marriage entered on or after January 1, 2026.3Rhode Island General Assembly. H5258 – Common Law Marriage Abolished New Hampshire recognizes these unions only for inheritance purposes: if two people live together and hold themselves out as married for at least three years, the surviving partner can inherit as a spouse after the other’s death.4New Hampshire Law Library. Common-Law Marriage: Read the Law About
To establish a common law marriage, both people must have legal capacity to marry, typically meaning they are of sound mind and at least 18.5National Conference of State Legislatures. Common Law Marriage by State They must live together continuously and present themselves to others as married. That “holding out” can look like filing joint tax returns, using a shared last name, listing each other as spouses on insurance forms, or introducing each other as husband and wife. Once established, the couple has the same legal rights as any formally married couple: Social Security spousal benefits, inheritance under intestacy laws, and spouse-based health insurance.
Because a valid common law marriage is legally identical to a ceremonial one, ending it requires a formal divorce. Moving to a state that doesn’t allow the creation of common law marriages doesn’t dissolve one already formed. Skip the divorce and enter a new relationship, and you risk bigamy charges.
Grandfathered Common Law Marriages
Several states abolished common law marriage but still recognize unions formed before a specific date. Georgia recognizes those created before January 1, 1997. Idaho’s cutoff is January 1, 1996. Ohio honors unions formed before October 10, 1991, and Pennsylvania recognizes those created before January 1, 2005.5National Conference of State Legislatures. Common Law Marriage by State Indiana’s cutoff goes back to January 1, 1958. If you believe your relationship predates the cutoff in one of these states, the marriage may still be legally valid, but the burden of proof falls on the person asserting it.
When one partner claims a common law marriage and the other denies it, courts examine the totality of the couple’s behavior: joint bank statements, shared property deeds, testimony from friends and neighbors, tax returns, insurance forms. No single factor is decisive.
Domestic Partnerships and Civil Unions
Several states offer domestic partnerships or civil unions as a formal way to gain legal recognition without marrying. California, Oregon, Washington, Maine, Nevada, Wisconsin, and the District of Columbia are among those with domestic partnership statutes.6National Conference of State Legislatures. Civil Unions and Domestic Partnership Statutes Colorado and several other states offer civil unions. Registration usually means filing a declaration with a state or local office such as the Secretary of State or a county clerk, and paying a filing fee that generally runs between $10 and $50.
Eligibility rules vary but commonly require partners to be at least 18, share a primary residence, and not be closely related. Registered partners gain state-level rights that can include hospital visitation, authority to make medical decisions for an incapacitated partner, inheritance protections, and eligibility for a partner’s employer-provided health insurance. Dissolving a domestic partnership typically requires a legal process similar to divorce, with a formal division of shared assets.
The federal government does not recognize domestic partnerships or civil unions for any purpose. Registered partners cannot file federal tax returns jointly; they file as single or, if eligible, as head of household.7IRS. Answers to Frequently Asked Questions for Registered Domestic Partners and Individuals in Civil Unions Domestic partners cannot sponsor each other for immigration benefits like spousal visas, and they are not eligible for Social Security spousal or survivor benefits based on the partner’s earnings record. Only a legal marriage, including a valid common law marriage, triggers those protections. A partnership registered in one state may also not be recognized by a neighboring state, so couples who move should confirm whether the registration still carries weight.
What Unmarried Couples Lose at the Federal Level
The federal tax code treats unmarried partners as strangers. Each files an individual return as single unless one qualifies for head of household by supporting a dependent child or qualifying relative.8IRS. Filing Status You cannot split income across returns, and you miss the wider tax brackets and higher standard deduction available to joint filers. For couples with significantly different incomes, the annual difference can be substantial.
Social Security is another gap that can total hundreds of thousands of dollars over a lifetime. An unmarried partner has no right to spousal benefits (up to 50% of a partner’s benefit) or survivor benefits (up to 100%) based on the other partner’s work record. One exception: if you were previously married to someone else for at least 10 years, you may collect on your ex-spouse’s record even after divorce.
Retirement accounts add another layer. Unmarried partners cannot roll over each other’s 401(k)s or IRAs tax-free after death the way a surviving spouse can. The inherited account is treated as a non-spouse beneficiary account, with stricter distribution timelines and potential tax consequences.
Inheritance Without a Will
If your partner dies without a will, you inherit nothing under state law. Every state’s intestacy statutes distribute assets to legal spouses, children, parents, and siblings, in that order. An unmarried partner does not appear anywhere on that list, regardless of how long you lived together or how much you contributed to shared property. A 30-year relationship with pooled finances gives you the same legal claim as a stranger.
The fix is deliberate but not complicated. A will naming your partner as a beneficiary is the minimum. A revocable living trust is stronger because it avoids probate entirely and is harder for family members to challenge. Title property carefully: if you want a shared home to pass to your partner, joint tenancy with right of survivorship accomplishes that automatically at death. Beneficiary designations on life insurance, retirement accounts, and bank accounts should name your partner directly, since these pass outside a will.
Medical and Financial Decision-Making
When a married person is hospitalized and incapacitated, their spouse has default legal authority to make medical decisions and access health information. An unmarried partner has no such right. Hospitals follow state priority lists that start with spouses and move through adult children, parents, and siblings. A long-term partner without documentation can be shut out of the room.
Three documents close the gap:
- A health care power of attorney, sometimes called an advance health care directive, names your partner as the person authorized to make medical decisions if you cannot. Without it, doctors turn to the nearest blood relative.
- A HIPAA authorization lets your partner access your medical records and speak with your doctors. Federal privacy law otherwise blocks providers from sharing that information.
- A durable financial power of attorney authorizes your partner to manage your finances, pay bills, access accounts, and handle property transactions if you become incapacitated. The agent has a fiduciary duty to act in your best interest.
All three should be signed while both partners are healthy and competent. Once incapacity strikes, it is too late. Each state has its own execution requirements, so use a state-specific form or work with a local attorney.
Cohabitation Agreements
A cohabitation agreement is a written contract between unmarried partners that spells out who owns what, how expenses are shared, and what happens to property if the relationship ends. These agreements are enforceable in most states as long as they meet basic contract requirements: both parties sign voluntarily, the terms are clear, and each side gives something of value beyond the relationship itself.
Courts will refuse to enforce an agreement whose only consideration is sexual services, which is treated as against public policy.9Justia. Marvin v Marvin Financial consideration works. Agreements involving real estate must be in writing and signed to satisfy the Statute of Frauds.10Cornell Law Institute. Statute of Frauds A well-drafted agreement typically covers:
- Property ownership, including anything brought into the relationship and anything acquired during it
- How rent or mortgage payments, utilities, and daily living costs are divided
- Which debts belong to each partner and whether any debts taken on during the relationship are shared
- Pet ownership and care, which several states now treat as enforceable contract terms rather than personal property disputes
Both partners should disclose their full financial picture before signing. Each having an independent attorney review the agreement makes it far harder for either side to later claim pressure or misunderstanding. A cohabitation agreement functions as a private set of rules that overrides the default state treatment of the parties as unrelated individuals.
If the Relationship Ends Without an Agreement
Without a written contract, the legal options narrow but do not disappear entirely.
Palimony and Implied Contracts
Palimony is a court-ordered support payment to an unmarried partner, similar to alimony. The concept took hold after the California Supreme Court’s 1976 decision in Marvin v. Marvin, which held that courts should enforce express and implied agreements between unmarried partners unless the sole consideration was sexual services.11Supreme Court of California. Marvin v Marvin Evidence like one partner leaving a career to manage the household, or both partners pooling income into a single account for years, can support an implied contract claim.
Most states do not have palimony statutes. Where it is available, it comes through case law rather than legislation, and the burden of proof is heavy. A majority of states will not award palimony at all, and the few that entertain these claims require strong evidence of an actual agreement, not just a long relationship.
Equitable Remedies
When property is titled in one partner’s name but both contributed financially, courts may use equitable doctrines to divide the asset. A resulting trust recognizes an ownership interest based on financial contribution: if you paid half the down payment on a home titled solely in your partner’s name, a court may find you own a proportionate share. A constructive trust is broader and can be imposed to prevent unjust enrichment; if you paid $50,000 to renovate a home you don’t own, a judge might grant you a share of the increased equity. Quantum meruit allows recovery for the reasonable value of services rendered when one partner provided labor or domestic services with the expectation of compensation.
These remedies are not available everywhere. Illinois is the most notable holdout. In Blumenthal v. Brewer (2016), the Illinois Supreme Court reaffirmed that the state does not recognize property claims arising from unmarried cohabitation, maintaining a position first established decades earlier.12Justia. Blumenthal v Brewer The court reasoned that recognizing such claims would effectively grant marriage-like rights without marriage. In states that follow this approach, the absence of a written agreement or marriage can leave a contributing partner with no legal recourse.
Children of Unmarried Parents
Children born to unmarried parents have the same legal right to support as children of married parents, but enforcing that right requires establishing legal paternity. Federal law requires every state to operate a voluntary acknowledgment of paternity program, available at hospitals and birth record agencies.13Office of the Law Revision Counsel. 42 USC 666 – Requirement of Statutorily Prescribed Procedures Both parents sign a form, and it carries the same legal force as a court order.
If paternity is not established voluntarily, either parent can petition a court for a determination, often involving genetic testing. Once legal parentage is established, child support obligations follow. Every state uses income-based guidelines factoring in each parent’s earnings, the number of children, and custody arrangements. Enforcement tools include wage garnishment, asset seizure, license suspension, and in extreme cases, jail time. Custody and visitation rights also flow from established parentage. Without it, an unmarried father may have no legal right to custody or even visitation, even after years of involvement in the child’s life.
Housing When You Split
If only one partner is on the lease or title, the other has no ownership or tenancy right simply because of the relationship. But that does not mean the homeowner can change the locks and put the other partner’s belongings on the curb. In most states, a person who has lived in a home for an extended period becomes a legal occupant, and removing them requires formal eviction proceedings through the courts. Self-help evictions like changing locks or shutting off utilities are illegal in virtually every jurisdiction. If both partners are on the lease, both remain liable for rent regardless of who moves out. If both names are on a mortgage or deed, the property must be divided through negotiation or, failing that, a court action for partition.