Common law marriage versus cohabitation is really a question about legal status: a common law marriage, where a state recognizes one, is a full marriage with every right and obligation that attaches to a ceremonial one, while cohabitation is the law treating two people as unrelated adults who happen to share an address. That difference drives nearly everything that follows, from how the IRS taxes you to whether you inherit your partner’s home.
The Core Legal Difference
A valid common law marriage is a marriage. The IRS, the Social Security Administration, and every state that recognizes it treat the couple as spouses, with the same filing status, survivor benefits, estate tax treatment, and divorce requirements as any other married couple. Cohabitation has no such status. However long the relationship lasts and however entangled the finances get, each partner remains, in the eyes of the law, a legal stranger to the other.
That stranger status is the point to hold onto. It means no automatic inheritance, no automatic authority at a hospital bedside, no joint tax filing, no Social Security survivor benefit, no marital deduction for property transfers. Rights that married couples take for granted have to be built one document at a time for unmarried partners, and anything they forget to put in writing defaults against them.
Where Common Law Marriage Still Exists
Only a handful of states allow new common law marriages. Colorado, Iowa, Kansas, Montana, South Carolina, Texas, and Utah permit them by statute. Rhode Island and Oklahoma recognize them through court decisions. New Hampshire takes an unusual approach, treating couples who lived together and held themselves out as married only after one partner dies, for inheritance purposes.1National Conference of State Legislatures. Common Law Marriage by State
Every other state has abolished the practice, though most will honor a common law marriage validly formed elsewhere. A marriage valid where it was created generally travels with the couple, so a Colorado common law marriage doesn’t dissolve when the couple moves to a state that no longer allows new ones. If you aren’t in a recognizing state and never were, living together does not make you married, no matter how long it goes on.
What It Takes to Qualify
No state creates a common law marriage just by counting years of cohabitation. That belief is probably the most widespread myth in family law. Every recognizing state requires three things at the same time: legal capacity, a mutual present agreement to be married, and public representation of the relationship as a marriage.
Legal capacity means both people are at least 18, mentally competent, and not already married to someone else. Colorado requires both parties to be 18 or older and the marriage to not be otherwise prohibited by law.2Colorado Department of Revenue. Common-Law Marriage Kansas has the same age requirement.1National Conference of State Legislatures. Common Law Marriage by State
The agreement element is what separates common law marriage from cohabitation. Both partners must intend, right now, to be married to each other. A plan to marry someday doesn’t count. Texas requires a couple to agree to be married, live together in the state, and represent to others that they are married.3State of Texas. Texas Family Code Chapter 2 – The Marriage Relationship Colorado requires the couple to have a reputation in the community as being married.2Colorado Department of Revenue. Common-Law Marriage
Public representation is where contested cases are won or lost. Courts look for joint tax returns filed as married, shared last names on financial accounts, insurance policies listing a spouse, and introductions to friends, family, and employers as husband and wife. A couple who keeps the relationship private or avoids the word “married” will struggle to prove this element later.
What Common Law Spouses Get That Cohabiting Partners Don’t
Joint Tax Filing
Couples in a recognized common law marriage may file federal income tax returns jointly under Section 6013 of the Internal Revenue Code. The IRS treats a common law marriage the same as a ceremonial one, and this remains true even if the couple later moves to a state that doesn’t recognize common law marriage.4Internal Revenue Service. Revenue Ruling 2013-17 Unmarried cohabiting partners cannot file jointly.
Social Security Survivor Benefits
A surviving common law spouse can collect Social Security survivor benefits like any other surviving spouse: full benefits at full retirement age (67 for anyone born in 1962 or later), reduced benefits as early as age 60, or benefits at any age while caring for the deceased worker’s child under 16.5Social Security Administration. Survivors Benefits The SSA asks for signed statements from the surviving spouse and blood relatives of the deceased to verify the marriage.6Social Security Administration. Code of Federal Regulations 404.726 – Evidence of Common-Law Marriage
An unmarried cohabiting partner receives nothing from Social Security when the other partner dies, regardless of how long they lived together or how financially dependent they were. For many couples, that single difference dwarfs every other item on this list.
Estate and Gift Tax Treatment
Married couples benefit from the unlimited marital deduction, which lets spouses transfer unlimited assets to each other during life or at death without triggering estate or gift tax.7Office of the Law Revision Counsel. 26 USC 2056 – Bequests, Etc., to Surviving Spouse8Office of the Law Revision Counsel. 26 USC 2523 – Gift to Spouse Common law spouses qualify. Unmarried partners do not.
Without the marital deduction, transfers between unmarried partners are subject to the standard gift tax annual exclusion of $19,000 per person in 2026.9Internal Revenue Service. Frequently Asked Questions on Gift Taxes Anything above that counts against the lifetime estate and gift tax exemption, which is $15,000,000 for 2026.10Internal Revenue Service. Whats New – Estate and Gift Tax Most people won’t hit the lifetime cap, but couples with significant real estate or retirement assets can run into gift tax issues faster than they expect when shifting property interests between partners.
Inheritance When There’s No Will
State intestacy laws decide who inherits when someone dies without a will, and they prioritize surviving spouses, children, parents, and siblings in that order. A common law spouse sits at the top of that list. An unmarried partner doesn’t appear on it at all. A partner of 30 years with no will could leave nothing to the person who shared every aspect of their life while a distant relative inherits everything. This is the single strongest reason for cohabiting couples to either formalize the relationship or, at minimum, draft wills and update beneficiary designations.
Property Ownership
Married couples get the automatic property-splitting rules of divorce if the marriage ends. Unmarried partners don’t. Whatever name is on the deed or title controls ownership. When both partners are on a deed, they typically hold the property as tenants in common, meaning each owns a defined share they can sell, transfer, or leave to anyone in a will. If one partner dies, the other does not automatically inherit the deceased partner’s share. Joint tenancy with right of survivorship, where the survivor automatically takes the whole property, must be explicitly created in the deed language.11Thomson Reuters Westlaw. Joint Tenancy with Right of Survivorship (JTWROS)
Medical Decisions
Hospitals default to legal family members when a patient cannot make their own decisions. An unmarried partner has no automatic authority to access medical records, make treatment calls, or even receive updates. A healthcare power of attorney solves this, but it has to be signed before the emergency. Some facilities also restrict visitation to legal family absent written documentation, so a hospital visitation authorization is worth considering alongside the healthcare proxy.
Closing the Gap Without Getting Married
Cohabiting couples who don’t want to marry, or who live in a state where common law marriage isn’t available, can replicate many of these protections through legal documents. None of it is automatic, and none of it is as clean as the married default, but the tools exist.
Cohabitation Agreements
A cohabitation agreement is a contract between unmarried partners that spells out financial rights and responsibilities during the relationship and after it ends. Courts in most states enforce these under ordinary contract law, as long as the agreement is in writing, signed voluntarily, and doesn’t rest on illegal terms. The California Supreme Court decision in Marvin v. Marvin established that courts should enforce express contracts between nonmarital partners, with the sole exception being agreements explicitly founded on sexual services.12Justia Law. Marvin v. Marvin That principle has been widely adopted.
A useful cohabitation agreement should cover:
- An asset inventory listing what each partner owns going in, including bank accounts, investment accounts, real estate, vehicles, and valuable personal property.
- Debt allocation, meaning who is responsible for existing debts like student loans and credit cards, and how new shared debt will be handled.
- Expense sharing rules for rent, utilities, groceries, and other household costs, whether equally or proportionally to income.
- How property purchased together during the relationship will be divided if things end.
- Whether either partner will receive financial support from the other after a breakup, and under what conditions.
Both parties should disclose all assets and debts fully, because a court can throw out an agreement built on hidden finances. Having each partner review the agreement with their own attorney strengthens enforceability. Courts will not enforce provisions that attempt to set child support, custody, or visitation terms; those are governed by state law and determined by the child’s best interests, not the parents’ contract. If the couple later marries, the cohabitation agreement typically stops applying and should be replaced with a postnuptial agreement.
Domestic Partnerships and Civil Unions
Several states offer a middle path through registered domestic partnerships or civil unions. These are formal legal statuses created by state statute that grant some or all of the rights and obligations of marriage. Colorado, Illinois, New Jersey, California, Oregon, Hawaii, and a handful of others maintain some version, though eligibility rules and the specific rights conferred vary widely. Registered partners often gain access to employer health insurance, hospital visitation, and some inheritance protections. The catch: these are creatures of state law, and federal agencies may not treat them as marriages for purposes like Social Security survivor benefits or joint tax filing. The details of a specific state’s program matter.
Children’s Legal Status
Children born to common law spouses benefit from the same legal presumption of parentage as children born to ceremonially married couples. The partner married to the birth parent at conception or birth is presumed to be the child’s legal parent, with all the custody rights, support obligations, and inheritance rights that follow. The presumption is rebuttable, but it provides immediate legal certainty.
Children born to unmarried cohabiting parents don’t get that automatic presumption in every situation. A father who isn’t married to the birth mother may need to establish parentage through a voluntary acknowledgment or a court proceeding. Once parentage is established, the child’s rights to support and inheritance are the same regardless of the parents’ marital status. But getting there can be contested and expensive, particularly if the relationship ends badly. Putting both parents’ names on the birth certificate is a good start, though it doesn’t substitute for formal legal parentage in every state.
How Each One Ends
Divorcing Out of a Common Law Marriage
A common law marriage is a real marriage, and ending one requires a real divorce. You file a petition for dissolution just as you would after a ceremonial wedding, and a judge issues a final decree resolving property division, support, and custody. Most jurisdictions impose a mandatory waiting period of at least 60 to 90 days.
One wrinkle unique to common law divorce: you may first need to prove the marriage existed before the court will dissolve it. If your partner disputes that a common law marriage was ever established, the case can split into two phases, with the first devoted entirely to whether there’s a marriage to dissolve.
Ending a Cohabitation Arrangement
Because cohabitation isn’t a marriage, there is no divorce. If you have a cohabitation agreement and your partner violates it, your remedy is a breach-of-contract lawsuit in civil court. Service of process to notify the other party typically costs between $20 and $100.13National Association of Professional Process Servers. How Much Does a Process Server Cost? These cases can take months and often settle.
Without a written agreement, dividing shared property depends on whose name is on which accounts and deeds. A partner who contributed to a home owned solely by the other may have a claim based on unjust enrichment or an implied partnership, but proving it without documentation is an uphill battle. The absence of a cohabitation agreement hurts most not during the relationship but after it ends.