This is one of the most important questions for couples who are not married in New Mexico, and the answer is more stark than most people expect. The legal protections that flow automatically to a spouse simply do not exist for an unmarried partner. The gap is not small. It covers inheritance, medical decision-making, financial authority during incapacity, and property rights.
No automatic inheritance rights
When someone dies without a will in New Mexico, their assets pass under the state's intestate succession law. That law distributes assets to biological relatives in a fixed order: children, parents, siblings, and more distant relatives. An unmarried partner is not in this hierarchy and receives nothing, regardless of how long the relationship lasted or how intertwined the couple's finances were.
This outcome is permanent and cannot be reversed after the fact. The only remedy is a will or other estate planning documents executed before death.
No automatic medical decision-making authority
New Mexico's Uniform Health-Care Decisions Act establishes a default hierarchy for who can make medical decisions when a patient lacks capacity. That hierarchy runs to a court-appointed guardian, then a spouse or domestic partner, then adult children, then parents, then siblings. An unmarried partner who is not specifically named in a healthcare power of attorney has no legal standing in this hierarchy.
In practice, this means that if an unmarried partner is hospitalized and unable to communicate, their partner of many years may be unable to speak with doctors, receive medical information, or make treatment decisions. The patient's parents or siblings, who may be estranged or out of contact, may have more legal authority than the person who lives with the patient and knows their wishes.
A healthcare power of attorney executed in advance resolves this entirely. It names the partner as the designated agent and gives them the legal authority to act.
No automatic financial authority during incapacity
Without a durable financial power of attorney, an unmarried partner has no legal authority to access their partner's bank accounts, pay their bills, manage their investments, or handle any financial matter during a period of incapacity. Financial institutions follow the law, and the law does not recognize an unmarried partner's authority.
To access a partner's accounts during a medical crisis, without a power of attorney, a family member would typically need to petition a court for a conservatorship, a process that is public, slow, and expensive.
No community property rights
New Mexico is a community property state, but community property rules apply only to married couples. Assets acquired during an unmarried relationship belong to whoever earned or purchased them, not equally to both partners. An unmarried partner who contributed financially to a home, a business, or other assets but whose name is not on the title has no automatic claim to those assets.
A cohabitation agreement can create contractual rights between unmarried partners that address shared property. Without such an agreement, each partner's rights are limited to what they can prove they own or what a court might recognize under other legal theories, which is an uncertain and expensive process.
New Mexico does not recognize common-law marriage
New Mexico abolished common-law marriage as of January 1, 2024. No matter how long an unmarried couple has lived together, cohabitation does not create a legal marriage or any of the rights that flow from marriage under New Mexico law.
The solution is deliberate planning
Every right an unmarried partner needs must be created through legal documents. A will, a durable financial power of attorney, a healthcare power of attorney, an advance directive, updated beneficiary designations, and potentially a cohabitation agreement or revocable living trust together create a framework that gives an unmarried partner the protections that marriage would otherwise provide automatically.
