Michigan cohabitation laws for unmarried couples give you almost none of the automatic legal protections that marriage provides. Michigan abolished common-law marriage on January 1, 1957, so living together — for a year or for forty — does not create rights to your partner’s property, income, estate, or medical decisions.1Michigan Legislature. Michigan Code 551.2 Whatever protection you have as an unmarried couple in Michigan comes from documents you sign, titles you hold jointly, and beneficiaries you name. Nothing happens by default.
One narrow exception: Michigan will recognize a common-law marriage that was validly formed in another state that permits them. A couple who has always lived in Michigan cannot create one no matter what they do.
Property and Money if You Break Up
When a married couple divorces, Michigan’s equitable distribution rules govern who gets what. Unmarried partners have no equivalent process. Property belongs to whoever holds legal title, and disputes get resolved under ordinary contract and property law.
That rule cuts hard. If you pay the down payment on a house but only your partner’s name is on the deed, you may have no legal claim to the home after a breakup. The same logic runs through everything else: bank accounts, vehicles, furniture, retirement accounts. If your name is not on it, you likely do not own it, regardless of how much you contributed.
Michigan also does not recognize palimony. There is no right to ongoing financial support from a former cohabiting partner the way there is after a divorce. Without a written agreement, courts have little basis to order any transfer of assets or support when an unmarried relationship ends.
Cohabitation Agreements
A cohabitation agreement is the single most important protective step an unmarried couple can take in Michigan. Courts treat these agreements as enforceable contracts, and they function much like prenuptial agreements. You and your partner spell out who owns what, how expenses get shared, what happens to jointly acquired property if the relationship ends, and whether either partner owes any support after separation.
A well-drafted agreement should cover, at minimum:
- Property ownership — which assets are individually owned, which are jointly held, and how joint property gets divided.
- Financial responsibilities — how rent, mortgage payments, utilities, and household expenses are split.
- Debt allocation — who is responsible for debts incurred during the relationship, individually and jointly.
- Separation terms — what happens to the shared residence, joint accounts, and accumulated assets if you split up.
Both partners should have independent legal counsel review the agreement before signing. An agreement drafted under pressure, without full financial disclosure, or where one party had no access to legal advice is more vulnerable to challenge later.
Children and Parental Rights
When married parents have a child, both spouses are automatically recognized as legal parents. Unmarried parents have to take an extra step. In Michigan, that step is completing an Acknowledgment of Parentage form, either at the hospital when the child is born or later at the local vital records office.2Michigan Courts. Establishing Paternity If the parents disagree about parentage, either parent or a prosecuting attorney can ask a court to establish it, which usually involves genetic testing and a hearing.
Establishing legal parentage is not optional if you want recognized parental rights. Without it, a non-birth parent may have no standing to seek custody or parenting time, no authority to make medical or educational decisions for the child, and no obligation to provide financial support. If the relationship ends, the parent without established legal parentage is in an extremely weak position.
Cohabiting parents should also consider formalizing custody and parenting time through a court order even while the relationship is stable. A court order creates enforceable terms. Informal arrangements can collapse overnight, and the parent without legal parentage may have no recourse.
What Happens If Your Partner Dies
This is where the gap between married and unmarried couples is most severe. If your partner dies without a will, you inherit nothing. Michigan’s intestate succession statute passes the estate to a surviving spouse first, then to descendants, parents, siblings, and more distant relatives. If no relatives can be found, the assets go to the state.3Michigan Legislature. Michigan Code 700.2101 An unmarried partner is not in the line of succession, no matter how long the relationship lasted.
Even assets you helped pay for can be lost. If only your partner’s name is on the deed, vehicle title, or bank account, their legal heirs inherit that property. You may have no legal claim even after years of contributing to it.
The only reliable protection is proactive estate planning. At a minimum, each partner should have:
- A will naming the other as a beneficiary, so assets go where you intend rather than following intestacy rules.
- Current beneficiary designations on retirement accounts, life insurance policies, and payable-on-death bank accounts. These pass directly to the named beneficiary regardless of what a will says or what intestacy law provides.
- Joint titling where appropriate. Property held as joint tenants with right of survivorship passes automatically to the surviving co-owner and bypasses probate.
Estate and gift tax treatment also cuts against unmarried couples. The federal estate tax marital deduction allows unlimited transfers between spouses with no tax consequences. Transfers to an unmarried partner are treated like transfers to any other individual and can trigger gift or estate tax liability above the applicable exclusion amounts.
Medical Decisions and Access
If your partner is unconscious in a hospital, you have no automatic right to make medical decisions or even access their health information. Michigan law reserves that authority for legal spouses and family members. The tool that changes this is a patient advocate designation, Michigan’s version of a healthcare power of attorney.
Under MCL 700.5506, any person 18 or older who is of sound mind can designate another adult to make care, custody, and medical decisions if they become unable to make those decisions themselves.4Michigan Legislature. Michigan Code 700.5506 – Designation of Patient Advocate The designation must be in writing, signed, dated, and witnessed by two people. Witnesses cannot be the patient’s spouse, parent, child, grandchild, sibling, presumptive heir, physician, or the designated advocate.
The designation takes effect only when the patient cannot participate in their own medical decisions, and it must be part of the patient’s medical record before it can be used. Without this document on file, hospital staff will turn to the patient’s legal next of kin, which does not include an unmarried partner. Completing this paperwork while both partners are healthy is one of the lowest-cost, highest-impact steps a cohabiting couple can take.
Taxes and Financial Transfers Between Partners
Federal tax law does not recognize cohabitation. Unmarried partners must each file as single, or as head of household if they qualify, even if they share every part of their financial lives. They cannot file a joint return.5Internal Revenue Service. Answers to Frequently Asked Questions for Registered Domestic Partners and Individuals in Civil Unions That locks them out of the married-filing-jointly brackets and the larger standard deduction available to married couples.6Internal Revenue Service. There’s More to Determining Filing Status Than Being Married or Single
Shared homeownership complicates deductions. If both partners are on the mortgage but only one itemizes, the mortgage interest deduction has to be allocated based on who actually paid. When payments come from a joint account with equal interests, each partner generally deducts half.7Internal Revenue Service. Other Deduction Questions Keeping clear records of who pays what avoids problems at tax time.
Asset transfers between unmarried partners can trigger gift tax. Married spouses have an unlimited gift tax marital deduction, so one spouse can transfer any amount to the other with no tax consequences.8Office of the Law Revision Counsel. 26 USC 2523 – Gift to Spouse Unmarried partners get no such benefit. Gifts between partners above $19,000 per year (the 2026 annual exclusion) may require filing a gift tax return.9Internal Revenue Service. Gifts and Inheritances 1 Helping a partner buy a car, paying off their student loans, or adding them to a property title can cross that threshold faster than people expect.
Cohabitation and Spousal Support From a Prior Marriage
Cohabitation can also matter for someone already receiving alimony from a previous divorce. Michigan law does not automatically end alimony when the recipient starts living with a new partner. Instead, MCL 552.28 gives courts authority to revise alimony judgments when either party petitions for a change.10Michigan Legislature. Michigan Code 552.28 – Judgment for Alimony or Allowance or for Appointment of Trustees; Revision or Alteration
To reduce or eliminate support, the paying ex-spouse generally has to show that the cohabitation has meaningfully changed the recipient’s financial situation. Michigan courts apply a fact-intensive test drawn from Smith v. Smith, looking at the living arrangement, the personal relationship, and the financial arrangements together.11FindLaw. Smith v Smith Simply sharing a home and expenses with someone — a parent, a platonic roommate — is not the same as entering a marriage-like partnership, and the outcomes turn on those details.