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Common Law Marriage in Montana

Montana recognizes common law marriage; the couple must be competent to marry, agree to be married and confirm it by cohabitation and public repute.

Last checked . General information, not legal advice.

Montana at a glance

New common law marriages allowed
Yes
Cutoff date
Not abolished
Requirements
Capacity, mutual consent, cohabitation, public repute
Under Montana case law the party claiming the marriage must prove each element by a preponderance of the evidence; short periods of cohabitation are not enough.

Sources

Last checked

The rules in Montana

Can a couple form a common law marriage in Montana today?

Yes. New common law marriages allowed in Montana: yes.

When did Montana stop recognizing new common law marriages?

Cutoff date in Montana: Not abolished.

What are the requirements for a common law marriage in Montana?

Requirements in Montana: Capacity, mutual consent, cohabitation, public repute. Under Montana case law the party claiming the marriage must prove each element by a preponderance of the evidence; short periods of cohabitation are not enough.

Where do the Montana common law marriage laws come from?

The rules above come from Mont. Code Ann. 40-1-403. Each source is linked on this page. We last checked them in October 2026.

What this means in practice

Living together for a long time does not by itself create a marriage. Where common law marriage is allowed, the key question is usually whether both partners agreed to be married and acted that way in public, for example by using the same last name, filing joint tax returns or calling each other husband or wife.

A valid common law marriage can only be ended by divorce or death, just like a licensed marriage. There is no informal way to undo it by moving out. The question of whether a marriage existed often comes up later, in a divorce, an inheritance dispute or a claim for spousal benefits.

Couples who want clear proof of their status can sign a written declaration or affidavit of marriage where state law provides for one, or simply obtain a marriage license. Couples who live together and do not want to be married can sign a cohabitation agreement that sets out how property and expenses are handled.

General information, not legal advice. Laws change, and cities can add their own rules, so check the current statute before you rely on it.