If a couple meets the state's specific requirements for a common law marriage, they are considered married. Those who benefit from common law marriage are people who cannot legally be married, such as same-sex partners, people who practice polygamy or people who cannot marry because they are too closely related to each other by blood.

If the couple lives in a state that recognizes common law marriages, spouses have the same rights of inheritance as a spouse in a legal marriage. Problems may occur if relatives of the decedent oppose a partner's claim of being a spouse. The common law spouse has to prove that the informal marriage was something more than a casual relationship. Costly and time-consuming litigation could easily result. Family members could also block a common law spouse from making medical decisions or even visiting the sick partner in the hospital.

People who enter into a common law marriage may think ending the marriage merely requires moving out. A person who wants to end a common law marriage must seek a formal divorce, the same way a person in a traditional marriage does. The court determines how to divide property, settle debts, and work out child custody arrangements. One partner may claim there never was an intention of marriage in an effort to avoid paying support or dividing property. The existence of joint tax returns or evidence of property taxes will clarify this issue. Neither spouse can remarry without the divorce.

At time of publication only 11 states and the District of Columbia permit common law marriages in some fashion while another five states allow the marriages under certain circumstances. Each jurisdiction has its own set of conditions to recognize a common law marriage. As an example, in Utah, a husband and wife must be capable of getting married and have the reputation of being married. In New Hampshire, common law marriages are recognized only for the purposes of inheritance. In South Carolina, the couple must intend others to believe they are married.