Montana recognizes common-law marriage, and a common-law marriage is as real as one that began with a license and a ceremony. That means ending it takes a divorce, which Montana calls a dissolution of marriage, with the same rules for property, support, and children. This page explains how courts decide whether a common-law marriage exists and what that means for a breakup. It is part of our Montana Divorce Guide.
Where the Rule Comes From
The marriage chapter of the Montana Code sets out the usual route: a license, solemnization, and registration. It then says, in MCA § 40-1-403, that "common-law marriages are not invalidated by this chapter." The legislature left the doctrine in place, and the details come from Montana Supreme Court decisions.
Montana's evidence statutes add a presumption that "a man and a woman deporting themselves as husband and wife have entered into a lawful contract of marriage" (MCA § 26-1-602(30)). The Supreme Court has described that presumption as rebuttable and as "one of the strongest known to the law" (In re Marriage of Swanner-Renner, 2009 MT 186, ¶ 16, 351 Mont. 62, 209 P.3d 238).
The Four Elements Courts Apply
The party seeking to establish a common-law marriage in Montana must show four things (Swanner-Renner, ¶ 17, restated in In re Estate of Zugg, 2025 MT 78, ¶ 9):
| Element | What must be shown |
|---|---|
| Competence | Both people were competent to enter a marriage. |
| Mutual consent and agreement | They assumed a marital relationship by mutual consent and agreement. |
| Cohabitation | They lived together. |
| Public repute | They acquired the reputation, character, and status of marriage in public. |
The court added that the parties must "enter upon a course of conduct to establish their repute as husband and wife." Consent is the element people overlook. Living together and sharing bills is not enough without an agreement between the two of you to be married.
Competence ties back to the statutes. A marriage entered into before an earlier marriage of one of the parties has been dissolved is prohibited (MCA § 40-1-401(1)(a)), so a person who is still married to someone else cannot form a common-law marriage with a new partner. The statute also says that parties who cohabit after the impediment is removed are lawfully married as of the date it was removed (MCA § 40-1-401(2)).
No Number of Years Creates One
You may have heard that living together for seven years, or some other period, makes a couple common-law married. Nothing in the Montana statutes or in the elements above sets a time period. Duration is not an element.
Time still matters as evidence. In Swanner-Renner, the Supreme Court overruled statements in older cases that a common-law marriage must come into being instantly or not at all. It reasoned that cohabitation and public repute cannot be established immediately and are "continuing factors that extend through the life of the marriage" (¶ 21). A long history of living as a married couple helps prove the elements. It does not replace them.
You Must Have Lived Together in Montana
Some states do not recognize common-law marriages formed within their borders. The Montana Supreme Court has addressed couples who began their relationship in such a state.
- In Swanner-Renner, a couple exchanged informal vows in Washington, which does not recognize common-law marriage, then moved to Montana and lived here as a married couple. The court held that once they relocated to Montana, the relationship ripened into a valid marriage under Montana law (¶ 20).
- In Estate of Zugg, a couple lived in North Dakota and Arizona and only visited Montana. The court held that without having lived in the state, the surviving partner could not establish a valid common-law marriage under Montana law (¶ 14).
If you formed a relationship elsewhere and later moved here, or moved away from Montana, which state's law applies is a question for a lawyer.
Ending a Common-Law Marriage Takes a Dissolution
There is no such thing as a common-law divorce. "A marriage may be contracted, maintained, invalidated, or dissolved only as provided by the law of this state" (MCA § 40-1-103). If you are common-law married, separating does not end the marriage, and neither of you can lawfully marry someone else until a court dissolves it (MCA § 40-1-401(1)(a)).
The dissolution itself works the same way as any other. Swanner-Rennerwas a dissolution case: one spouse filed a petition, the district court held a hearing on whether the parties were married, found that they were, and then dissolved the marriage and divided the property. On appeal the Supreme Court applied the ordinary property statute, MCA § 40-4-202, and sent the case back for findings on one spouse's contribution to the increased value of a ranch (¶¶ 34 to 37).
So every topic in this guide applies: property division, maintenance, and parenting plans. Start with how divorce works in Montana.
When One of You Says There Was No Marriage
The stakes of this dispute are high. If there was a marriage, the court equitably apportions property belonging to either or both spouses (MCA § 40-4-202(1)) and may consider maintenance. If there was not, those statutes do not apply, and any claims between former partners rest on other areas of law.
The person asserting the marriage has to prove the elements. The opinions we read point to the kinds of evidence courts weigh: how each person described the relationship under oath, tax filing status, benefit and insurance forms naming a spouse, a signed declaration of marriage, and whether friends, family, and the community knew the couple as married. No single document decides it, and a court also judges credibility.
A person who lived with another in the good faith belief that they were married has separate protection as a putative spouse (MCA § 40-1-404). And parents do not need to have been married for a court to adopt a parenting plan or order child support. See our paternity page.
Same-Sex Couples
The presumption statute and the older cases speak of "a man and a woman." In Obergefell v. Hodges, 576 U.S. 644 (2015), the United States Supreme Court held that states may not exclude same-sex couples from civil marriage on the same terms and conditions as opposite-sex couples. The Montana opinions discussed on this page involved opposite-sex couples, so how the elements apply to a same-sex couple, especially for years before 2015, is a question to take to a lawyer. See same-sex divorce in Montana and our LGBT family law page.
This page explains Montana law in general as of the 2025 Montana Code Annotated. It is not legal advice about your specific situation.