I posted this sometime ago. It still holds.
There is no such thing as a "common law marriage" in the Dominican Republic. Living together, our Supreme Court has said, is never equivalent to a normal marriage.
However, certain provisions in the Labor Code, the Minors Code and the Criminal Code acknowledge that living together has legal consequences. For example, a worker has the right to a few days off work if his or her companion gives birth to his child; domestic violence to a companion treated the same as domestic violence to a wife. On October 17, 2001, a Supreme Court decision gave a surviving concubine the right to sue for the wrongful death of her companion in an automobile accident under very restrictive conditions: a) the couple must have lived as if they were husband and wife, in a public relationship, not hidden or secret; b) the relationship must be stable and long-lasting; c) the relationship must be monogamous and non-adulterous since its origins ; and d) the couple should be of different sexes. The ruling goes on to say expressly that "marriage and extra matrimonial companionship are not . . equivalent realities”.
During the present decade, lower courts have expanded these rights to other areas, giving the "common-law wife" ("concubina" in Doiminican legal terminology) rights in the estate of her "common-law husband" or rights to "community property" in case of separation. Recently, however, the Supreme Court rejected the claim made by a surviving companion to 50% of her deceased companion's estate. The claimant had argued that her lifelong relationship should be equivalent to marriage under community-property rules.
The new Constitution, in article 55 regarding the family, although it acknowledges that a free union generates rights and obligations, adds at the end "de conformidad con la ley" ("in accordance with the law"), and the law has not changed. The Constitution, in effect, is just reproducing the doctrine set by the Supreme Court in 2001. My sense is that the Catholic Church, who has been so influential in the drafting of the Constitucion (Art. 37. "The right to life is inviolable from conception until death".) opposed any opening in this regard.
Conclusion: the law is in flux. If what is desired is certainty of outcome, my recommendation is to get married with a prenuptial agreement.