http://www.aaml.org/common.htm
"If the parties to an informal union each have the legal capacity to marry, prima facie evidence of the existence of a common-law or informal marriage may be established by a properly executed and recorded declaration of informal marriage. Husband v. Pierce, 800 S.W.2d 661, 663 (Tex. App. -- Tyler 1990, no writ). In order to enter into any form of valid marriage in Texas, whether ceremonial or common-law, the parties must possess the requisite legal capacity to marry. The parties desiring to be married in Texas must:
(1) be of the opposite sex [TEX. FAM. CODE § 1.01);
(2) each have not been divorced from a third party within the past 30 days [TEX. FAM. CODE § 1.03];
(3) not be currently married to a third party [TEX. FAM. CODE § 1.03];
(4) be 18 years of age [TEX. FAM. CODE § 1.51], unless the underage party has secured a waiver of the age requirement from the court [TEX. FAM. CODE § 1.53], or has proof of parental consent [TEX. FAM. CODE § 1.52]; and,
(5) not be related as an ancestor or descendant, related by blood or adoption, nor be siblings by whole, half blood or by adoption, nor may either be a parent’s brother or sister by whole or half blood, nor be the son or daughter of a brother or sister by whole or half blood [TEX. FAM. CODE §§ 1.03 and 1.92]"
"Under § 2.22 of the Texas Family Code, "[a] marriage is void if either party was previously married and the prior marriage is not dissolved. However, the marriage will become valid if the prior marriage is dissolved and if, since the time the parties have lived together as husband and wife, they represented themselves to others as married. After the impediment to the marriage is removed, property rights will accrue. The validity of a marriage begins when a party’s divorce from a spouse of a prior marriage is final, and not from the date the parties to the putative marriage participated in a marriage ceremony. Caddel v. Caddel, 486 S.W.2d 141, 145 (Tex. Civ. App. -- Amarillo 1972, no writ)."
"If the parties each know of an impediment to the marriage, and assume marital relations in spite of this knowledge, the relationship is meretricious as to both parties. Curtin v. State, 238 S.W.2d 187, 190 (Tex. Crim. App. 1950)."
