New Mexico's estate planning laws were built around a marriage-centered model. The default rules, the ones that apply when someone dies without a will or without the right documents in place, assume a spouse. They give a spouse rights. They protect a spouse's financial position. They put a spouse first in the hierarchy for medical decision-making and financial authority during incapacity.
If you are not married to the person you live with, love, and plan your life around, those defaults do not apply to you. Your partner has no automatic inheritance rights under New Mexico law. Your partner has no automatic authority to make medical decisions for you. Your partner cannot access your financial accounts during a crisis without legal documentation giving them that authority. And if you die without a will, your assets pass to your biological relatives in a fixed order that may not include your partner at all.
This is not a gap that solves itself with time. New Mexico does not recognize common-law marriage. No matter how long you and your partner have lived together, shared finances, or built a life, the law treats you as legal strangers unless you have taken affirmative steps to create legal rights between you.
Estate planning is how unmarried couples create those rights. This article explains what's at stake and what to do about it.
The Common-Law Marriage Myth
One of the most persistent misconceptions among unmarried couples in New Mexico is that living together for a certain number of years creates a legal marriage. It does not. New Mexico abolished common-law marriage as of January 1, 2024 under legislation that made New Mexico one of the majority of states that do not recognize this doctrine.
This means that no matter how long you and your partner have been together, how intertwined your finances are, or how you present yourselves to the world, you are not legally married in New Mexico unless you went through a formal marriage ceremony or a legal process that created a valid marriage.
The practical consequence is that all of New Mexico's marriage-based default protections, the right to inherit under intestate succession, the right to make medical decisions, the right to manage community property, apply only to legally married spouses. For unmarried couples, every one of those protections must be created deliberately through legal documents.
What Happens Without an Estate Plan
When an unmarried person dies without a will in New Mexico, their estate passes under the state's intestate succession laws, codified under NMSA 1978, Chapter 45, Article 2. That law distributes assets in a fixed order: first to children, then to parents, then to siblings, then to more distant relatives. A domestic partner, no matter how long-standing or committed the relationship, is not in this hierarchy. They inherit nothing.
This outcome is not hypothetical. It plays out in New Mexico courts when a long-term partner dies without a will and the deceased's biological family, sometimes estranged, sometimes unknown, inherits everything. The surviving partner may have contributed financially to the home, the business, or the assets that are now passing to people who were not part of the relationship. Without a will, there is no legal mechanism to redirect that outcome.
The same problem applies to incapacity. If an unmarried partner becomes incapacitated without a financial power of attorney in place, their partner has no legal authority to manage their accounts, pay their bills, or handle their financial affairs. If there is no healthcare power of attorney, the partner has no legal authority to make medical decisions. Hospitals and financial institutions will follow the default legal hierarchy, which does not include an unmarried partner.
What an Estate Plan for Unmarried Couples Should Include
Wills
A will is the foundational document that allows an unmarried person to direct their assets to a partner at death. Without a will, New Mexico's intestate succession law controls, and an unmarried partner receives nothing.
A will for an unmarried person in a committed relationship should name the partner as the primary beneficiary for assets that pass through the will, name a successor beneficiary in case the partner predeceases, name the partner as personal representative to manage the estate administration, and address any assets the person wants to direct to family members or others in a way that reflects their actual wishes.
One important limitation: a will controls only assets that pass through probate. Assets that have a beneficiary designation or a joint ownership structure pass outside the will entirely. For unmarried couples, coordinating the will with beneficiary designations on retirement accounts and life insurance is essential.
Powers of Attorney
A durable financial power of attorney names the partner to manage financial affairs during incapacity. Without this document, a partner has no legal authority to access accounts, pay bills, manage investments, or handle any financial matter on behalf of the incapacitated person.
A healthcare power of attorney names the partner to make medical decisions during incapacity. Without this document, a partner has no right to receive medical information, speak with doctors, or make treatment decisions. New Mexico's default hierarchy for medical decision-making runs to spouses, then parents, then adult children, then siblings. An unmarried partner is not in this hierarchy.
Both documents are essential for unmarried couples and should be executed as part of any complete estate plan.
Advance Healthcare Directive
An advance healthcare directive, using New Mexico's Optional Advance Directive for Health Care, records the person's specific wishes about medical treatment. It also names the healthcare agent to carry out those wishes, which for an unmarried couple should be the partner.
Without an advance directive, the healthcare agent named in the healthcare power of attorney is left making decisions without written guidance. Combined, the healthcare power of attorney and the advance directive give the partner both the authority to act and the instructions to guide their decisions.
Beneficiary Designations
Retirement accounts, life insurance policies, and payable-on-death bank accounts pass directly to whoever is named on the beneficiary designation form, outside of probate and outside of the will. For an unmarried couple, naming the partner as the beneficiary on these accounts is often the most immediate and significant financial protection available.
This step does not require a will or any legal drafting. It requires contacting each financial institution and insurance company, requesting a change of beneficiary form, and designating the partner. But it should be done deliberately and reviewed regularly, because a designation made years ago may name a family member or a prior partner who is no longer the intended recipient.
For retirement accounts governed by federal ERISA law, including 401(k) plans and most pension plans, a current spouse has default rights to certain benefits that a named beneficiary cannot override without the spouse's consent. For unmarried partners, this issue does not arise, but it is still important to name the partner explicitly rather than leaving the designation blank or pointing to the estate.
Revocable Living Trust
A revocable living trust offers several advantages for unmarried couples beyond what a will alone provides. Assets held in the trust pass to beneficiaries without probate, which means the transfer is private and efficient. The trust can also manage assets during incapacity, giving the partner access through the trustee role or the successor trustee designation without any court involvement.
For couples who own a home together, a trust can also clarify the ownership structure and provide a clear mechanism for the home to pass to the surviving partner at death, regardless of how the deed is currently titled.
A trust is not necessary for every unmarried couple, but for couples with significant assets, real estate, or complex family situations, it is often the most comprehensive tool available.
Cohabitation Agreement
A cohabitation agreement is a contract between unmarried partners that establishes their financial rights and obligations toward each other. It can address how property acquired during the relationship is owned, how shared expenses are handled, what happens to shared property if the relationship ends, and how specific assets are treated.
New Mexico does not have a statutory framework for domestic partnerships that provides automatic property rights the way marriage does, which means unmarried couples who want legal clarity about shared property need to create that clarity themselves. A cohabitation agreement is the mechanism for doing that.
A cohabitation agreement is particularly useful for couples who have been together long enough to accumulate shared assets, who have made financial decisions based on an implicit understanding of how their property would be divided, or who want to ensure that a breakup or death produces a defined outcome rather than a dispute.
Real Property: Titling the Home
How a home is titled is one of the most important decisions an unmarried couple can make. Unlike married couples in New Mexico, who hold community property with automatic co-ownership rights, unmarried couples hold real estate however they choose to title it and in whatever proportions they specify in the deed.
Common options for an unmarried couple purchasing a home together include:
Tenants in common. Each partner owns a specified percentage of the property. At death, each partner's share passes through their estate, either by will or by intestate succession if there is no will. Without a will, the deceased partner's share passes to their biological heirs, not to the surviving partner.
Joint tenants with right of survivorship. At death, the property passes automatically to the surviving partner outside of probate. This is the simplest mechanism for ensuring the home passes to the surviving partner, but it gives each partner equal rights to the property during their lifetimes and may have gift tax implications if the contributions to the purchase were unequal.
Ownership through a trust. The home is held in a revocable living trust, with both partners as trustees and beneficiaries during their lifetimes. The trust specifies what happens to the home at the death of either partner and can be structured to reflect unequal contributions, specific conditions, or other arrangements that a simple deed cannot capture.
The right titling depends on the couple's specific situation, their contributions to the purchase, their intentions for the home, and their broader estate planning goals. An estate planning attorney familiar with New Mexico real estate law can help navigate the options.
Children in Unmarried Couples' Estate Plans
For unmarried couples who have children together, additional planning is necessary. A biological parent has legal rights to custody and support regardless of marital status. But other aspects of child-related planning, including guardianship nominations and trusts for minor children, require the same deliberate documentation for unmarried couples that they require for anyone.
If an unmarried partner has children from a prior relationship who are not the biological children of the current partner, those children have no automatic legal relationship with the current partner. The current partner has no automatic right to custody, no automatic right to adopt, and no automatic standing in a guardianship proceeding. Planning that addresses the children's care and financial support in the event of the biological parent's death is important for any unmarried couple in this situation.
How Genus Law Group Can Help
Estate planning for unmarried couples requires more deliberate effort than estate planning for married couples, because the legal defaults that protect married spouses simply do not apply. Every protection needs to be created through a document. Every right needs to be established explicitly.
At Genus Law Group, we help unmarried couples in Albuquerque, Las Cruces, and throughout New Mexico build complete estate plans that reflect their relationships and their goals. We take the time to understand your specific situation before recommending any documents.
Call us at (505) 317-4455 in Albuquerque or (575) 215-3500 in Las Cruces, or reach us through the contact form at genuslawgrp.com.
Frequently Asked Questions
Does New Mexico recognize common-law marriage?
No. New Mexico does not recognize 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 in New Mexico, and none of the rights that flow from marriage, including inheritance rights, spousal authority during incapacity, and community property ownership, apply to unmarried partners.
Can my unmarried partner make medical decisions for me in New Mexico if I become incapacitated?
Not without a healthcare power of attorney naming them as your agent. New Mexico's default hierarchy for healthcare decision-making 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 to make medical decisions, receive medical information, or speak with your care team on your behalf.
What happens to our shared home if one of us dies without a will?
It depends on how the home is titled. If the home is held as joint tenants with right of survivorship, it passes automatically to the surviving partner outside of probate. If the home is held as tenants in common with each partner owning a percentage, the deceased partner's share passes through their estate. Without a will, that share passes under New Mexico's intestate succession law to the deceased partner's biological heirs, not to the surviving partner.
Is a cohabitation agreement legally enforceable in New Mexico?
New Mexico courts generally enforce cohabitation agreements between unmarried partners as contracts, provided they meet the standard requirements for a valid contract: offer, acceptance, consideration, and mutual assent. Courts have declined to enforce cohabitation agreements that are based solely on a promise of future sexual services, but agreements that address property rights and financial obligations in a committed relationship are treated differently. Working with an attorney to draft a cohabitation agreement ensures it is structured in a way that is enforceable.
Do we need separate wills or can we have a joint will?
Separate wills are strongly recommended. A joint will, a single document signed by both partners, is legally recognized in some jurisdictions but creates significant complications because it typically cannot be changed after one partner dies. Most estate planning attorneys advise against joint wills for this reason. Two separate wills, each drafted to complement the other, give both partners flexibility and ensure that both plans remain adjustable as circumstances change.
