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In Colorado, the elements of a common-law marriage are, with respect to both spouses: (1) holding themselves out as husband and wife; (2) consenting to the marriage; (3) cohabitation; and (4) having the reputation in the community as being married. Different sources disagree regarding the requirement of cohabitation and some indicate that consummation(i.e. post-marital sexual intercourse) is also an element of common law marriage. Colorado, by statute, no longer recognizes common law marriages entered by minors in Colorado, and also does not recognize foreign common law marriages entered into by minors, even if that marriage would have been valid where entered into under local law. See Section 14-2-109.5, Colorado Revised Statutes.
There is NO time requirement here. So you could, theoretically, be common law married for a single day. The only proof that you need is to establish those four elements. So holding out and having reputation can be testified to by friends, family, etc... Cohabitation means living together. And consenting to the marriage generally is based upon testimony by one of or both of the spouses. Again, there's no specific time limit, and even a day could result in a common law marriage.
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