Colorado is one of the few states where a couple can be legally married without a license, a ceremony, or an officiant. A Colorado common law marriage is formed when two adults mutually agree to be married and then live in a way that shows that agreement to the people around them.1In re Marriage of Hogsett & Neale, 478 P.3d 713 (Colo. 2021) Once that happens, the marriage carries every right and duty of a licensed one, and it can only be ended by a court.
How a Common Law Marriage Is Formed
Colorado has no statute listing the elements. The rules come from case law, and the current framework is the Colorado Supreme Court’s 2021 decision in In re Marriage of Hogsett & Neale. Under Hogsett, a common law marriage exists when two people mutually agree to enter the legal and social institution of marriage and then act consistently with that agreement.
The agreement does not require a dramatic moment or any particular words. Courts weigh the totality of the circumstances. Shared finances, joint tax returns, a common last name, referring to each other as spouses, and listing one another as spouses on insurance or loan paperwork all point toward marriage. No single factor is required, and no single factor is enough on its own. The picture as a whole has to show two people who intended to be married and behaved that way.
A few things Colorado does not require tend to surprise people. There is no minimum period of living together. A couple could qualify after weeks if the intent and conduct are both there. Cohabitation on its own, though, is never enough. Plenty of couples share a home for decades without ever forming a common law marriage, because they never agreed to be married. Intent is what separates a long partnership from a legal marriage.
Who Can Form One
Since September 1, 2006, both parties must be at least eighteen. A common law marriage involving anyone under eighteen will not be recognized in Colorado, regardless of parental consent. Neither person can already be married to someone else, and the marriage cannot otherwise violate Colorado’s prohibited-marriage rules.
Both people must also have the mental capacity to consent. Someone who cannot understand what marriage means cannot form one. These capacity rules match what applies to any ceremonial marriage.
Proving It Later
The practical difference between a common law marriage and a licensed one is proof. A couple with a marriage certificate can hand it to a judge. A common law couple has to reconstruct the relationship through documents and testimony, and this comes up constantly in disputes over property, inheritance, and support.
Evidence courts find persuasive includes joint bank accounts, shared property deeds, insurance policies naming each other as spouses, jointly filed tax returns, and loan applications identifying the couple as married. Testimony from friends, family, or coworkers who understood the couple to be married carries weight too. Hogsett told courts to look at the full picture rather than check off a rigid list, and to give significant weight to an express agreement to marry when one exists.
The burden falls on whoever is claiming the marriage. In an inheritance fight, the surviving partner has to prove the marriage to claim spousal rights. In a divorce, the partner asking for property division or maintenance has to establish the marriage first. Claims often fall apart here: couples who lived together for years but never told anyone they were married, never filed taxes jointly, and never used each other’s names face a steep climb.
Filing an Affidavit
Colorado lets couples file a signed, notarized affidavit of common law marriage with the county clerk and recorder where they live. The affidavit is filed as a document, not as a marriage record. In it, both parties confirm they are at least eighteen, that no legal impediment exists, and that they consider themselves married. Filing the affidavit does not create the marriage. The agreement and the conduct do that. But it makes the marriage much easier to prove if anyone questions it later.
What Rights and Duties Come With It
Once a common law marriage exists, it carries the identical legal weight of a ceremonial one. There is no lesser tier.
Property and Inheritance
A common law spouse has the same property rights in a divorce as any other spouse. Colorado follows equitable distribution, meaning the court divides marital property fairly based on each spouse’s financial situation, contributions, and future needs. Fairly does not always mean equally, and the court has broad discretion.
If one spouse dies without a will, the surviving common law spouse inherits under Colorado’s intestacy statute. When the deceased has no surviving descendants or parents, or when all descendants are also descendants of the surviving spouse, the surviving spouse takes the entire estate. When the deceased has descendants from another relationship, the surviving spouse receives the first $150,000 plus half the remaining balance.
Spousal Maintenance
A common law spouse can seek spousal maintenance in a divorce, and the court applies the same factors it would in any marriage. Colorado uses advisory guidelines for marriages lasting at least three years when the couple’s combined adjusted gross income does not exceed $240,000. Under those guidelines, the monthly maintenance amount is 40% of the couple’s combined monthly adjusted gross income minus the lower-earning spouse’s monthly income. Duration scales with the length of the marriage.
Children
If the couple has children, both spouses have full parental rights and obligations, including custody, parenting time, and child support, on the same terms that apply to any married couple.
Medical Decisions
A common law spouse has the same authority as a ceremonially married one to make medical decisions for an incapacitated partner. Federal regulations also protect the right of patients in Medicare- and Medicaid-participating facilities to receive visits from a spouse, including a common law spouse.
Taxes
Once a common law marriage exists, the IRS treats the couple as married. The IRS recognizes a common law marriage if it is valid under the law of the state where the couple lives or where the marriage began. That means Colorado couples in a valid common law marriage must file as married filing jointly or married filing separately. Reporting yourself as single when you are legally married, intentionally or by oversight, can trigger audits, penalties, or in serious cases charges for tax fraud.
Recognition Across State Lines and by Federal Agencies
A valid Colorado common law marriage does not disappear at the state border. Under the Full Faith and Credit Clause, other states generally recognize a marriage that was valid where it was formed, even if the new state does not permit its own residents to create common law marriages.
Federal agencies apply the same rule. The Social Security Administration determines validity under the law of the state where the couple lived, and a surviving common law spouse can claim survivor benefits with proper documentation. SSA typically asks each spouse to complete a Statement of Marital Relationship (SSA-754) along with statements from blood relatives or others who can confirm the marriage, backed by joint financial records, insurance policies, and medical records. The Department of Veterans Affairs recognizes a common law marriage for spousal benefits if it is valid under the law of the state where the veteran lives. USCIS recognizes valid common law marriages for visa sponsorship and naturalization on the same “valid where formed” principle.
Employer Benefits and Retirement Accounts
Enrolling a common law spouse in an employer health plan usually requires more documentation than a ceremonially married spouse would need. Private employers set their own requirements, which commonly include a signed affidavit, proof of shared residence, and joint financial records. Expect some back-and-forth with HR if your employer has not handled one before.
Retirement accounts carry an important wrinkle. Under federal law governing most 401(k) and pension plans, a surviving spouse is automatically the primary beneficiary. Naming anyone else requires the spouse to sign a written waiver witnessed by a notary or plan representative. This applies equally to common law spouses. If you formed a common law marriage after enrolling in a retirement plan, tell the plan administrator, so your spouse’s automatic beneficiary rights are properly documented.
Ending a Common Law Marriage
There is no such thing as a common law divorce. A common law marriage can only end through a formal court divorce, the same as any other marriage. One spouse files a petition for dissolution, and at least one spouse must have lived in Colorado for 91 days before filing. The court then handles property division, maintenance, and, if children are involved, custody and support. If the other side disputes that a marriage ever existed, the spouse seeking divorce has to prove the common law marriage first before the court will divide anything. That preliminary fight can add real time and expense.
Why Walking Away Does Not Work
Some couples assume they can end a common law marriage by moving apart. They cannot. Without a divorce decree, both spouses remain legally married. Anyone who marries someone else while still in a common law marriage commits bigamy, a class 2 misdemeanor in Colorado. An undissolved common law marriage can also complicate property ownership, tax filing status, benefit eligibility, and inheritance rights for years. If there is any real chance a common law marriage existed, a formal divorce is the only clean way to close it.