In the United States, healthcare is not a citizenship right. It is an employment benefit, a market purchase, or, for the elderly and very poor, a means-tested or age-tested entitlement. Marriage is one of the few legal mechanisms that lets a person access another person's healthcare benefits. This makes marriage, for tens of millions of Americans, the most efficient path to insurance.
The mechanics are mundane. An employer-sponsored health plan typically allows a worker to enroll a spouse and dependent children. The premium is often subsidized by the employer. The spouse, who may not work or may work for an employer without health benefits, gains coverage they could not otherwise afford. This is the basic American health-insurance-through-marriage transaction, and it explains a substantial portion of the country's marriage decisions among the working-age population. Surveys consistently find that a non-trivial share of marriages — and a larger share of marriage timing decisions — are influenced by health insurance considerations.
Medicare adds another layer. A worker who has not earned enough Social Security credits to qualify for Medicare Part A on their own can qualify on a spouse's record after the spouse turns 62 and the marriage has lasted at least one year. This means marriage can be a path to Medicare eligibility for people who would otherwise face uninsured old age or expensive private coverage. Survivors and divorced spouses also have derivative Medicare rights in some circumstances.
The Affordable Care Act, passed in 2010, partially decoupled health insurance from marriage by creating individual markets with premium tax credits. For the first time, an unmarried adult earning a modest income could buy subsidized coverage without needing access to a spouse's plan. The ACA reduced — but did not eliminate — the marriage-health-insurance linkage. Premium tax credits phase out based on household income, so marrying a higher-earning spouse can eliminate subsidies. Employer plans continue to offer spousal coverage at terms generally more favorable than the individual market. Medicaid eligibility rules vary by state but often count spousal income.
The healthcare system also uses marriage as a default decision-making rule. When a patient is incapacitated, the spouse is the default surrogate decision-maker in nearly every state. This default can be overridden by a healthcare power of attorney, but most people do not have one. The spouse decides about ventilators, surgery, and end-of-life care. Hospital visitation, historically restricted to "immediate family," has been clarified by federal regulation (2010 CMS rule under HHS) to include spouses regardless of sex, but the spousal default remains the path of least resistance. Unmarried partners who want similar authority must execute legal documents and often must defend them at the hospital.
Long-term care brings its own marital architecture. Medicaid is the primary payer for nursing home care in the U.S., but its asset and income tests are strict. Spousal impoverishment rules allow the community spouse (the one not in the nursing home) to retain a certain amount of assets and income — a partial protection against the spend-down of marital wealth. The rules are complex and vary by state, and they make marriage relevant to long-term care planning in ways most couples do not contemplate until a health crisis forces the issue.
Naomi Cahn and June Carbone have written about how healthcare access through marriage interacts with class and race. Couples in stable, benefits-covered employment can access spousal coverage easily; couples in gig or low-wage work cannot, because their jobs do not offer the benefits to extend. The marital health-insurance subsidy thus accrues disproportionately to higher-income couples whose employers offer family coverage. The ACA narrowed the gap; it did not close it.
Margaret Stock and others have written about how the U.S. healthcare system's marital architecture interacts with immigration. A foreign spouse of a U.S. worker can access employer health coverage even before completing immigration paperwork in many cases. Conversely, an undocumented spouse may be excluded from Medicaid in restrictive states, even when their U.S.-citizen spouse qualifies.
The honest summary: marriage in the U.S. is a healthcare access mechanism in ways that are obscured by the romantic frame. For people without their own coverage, the decision to marry often includes a calculation about insurance, even when neither partner articulates it. The state has built a healthcare system that requires either employment, age, poverty, or marriage to access — and for many adults, marriage is the most achievable of those routes.