"Our formulations of the requirement of conduct manifesting or confirming the parties' understanding or agreement have taken many forms. See, e.g., Graham v. Graham, 130 Colo. at 227, 274 P.2d at 606 (to establish the agreement there must be evidence both of cohabitation and reputation); In re Estate of Danikas, 76 Colo. 191, 194, 230 P. 608, 610 (1924) (illicit cohabitation will not support reputation as proof of marriage; reputation alone is not enough); Smith v. People, 64 Colo. at 294, 170 P. at 960 (consent may be inferred from cohabitation and repute; cohabitation is "holding forth to the world by the manner of daily life, by conduct, demeanor, and habits, that the man and woman have agreed to take each other in marriage and to stand in the mutual relation of husband and wife."); see Taylor v. Taylor, 10 Colo. App. at 305, 50 P. at 1049 (1897) (agreement may be presumed from evidence of cohabitation and repute; general reputation or repute means "the understanding among the neighbors and acquaintances with whom the parties associate in their daily life, that they are living together as husband and wife....") The two factors that most clearly show an intention to be married are cohabitation and a general understanding or reputation among persons in the community in which the couple lives that the parties hold themselves out as husband and wife. Specific behavior that may be considered includes maintenance of joint banking and credit accounts; purchase and joint ownership of property; the use of the man's surname by the woman; the use of the man's surname by children born to the parties; and the filing of joint tax returns. See Mills, Common Law Marriage in Colorado, 16 Colo. Law. 252, 257 (1987). However, there is no single form that any such evidence must take. Rather, any form of evidence that openly manifests the intention of the parties that their relationship is that of husband and wife will provide the requisite proof from which the existence of their mutual understanding can be inferred."
