The US has no universal public health insurance for working-age adults: coverage comes from employer-sponsored plans, individually purchased ACA marketplace policies, means-tested Medicaid (largely unavailable to new immigrants), or going without, while Medicare is reserved for those 65+ (or disabled) who separately qualify. Here is what that actually means for an American or Briton living in the United States: what the public system gives you, what it does not, and where private cover fits.
Can you use the public system?
- Working for a local employer: No
- Self-employed: No
- Retired or not working: Only in limited cases
A working-age UK expat (employed or self-employed) has no public insurance option at all: they must get coverage through an employer plan or buy an individual policy on the ACA marketplace (healthcare.gov), with eligibility for premium subsidies depending on immigration status and increasingly restricted for many lawfully-present categories from 2026 onward. Medicare, the one public program relevant to older arrivals, generally requires the individual’s own 40 US work quarters (10 years of payroll tax) or a spouse’s equivalent record for premium-free Part A at 65; someone without that history can only buy into Medicare at all once they are a lawful permanent resident (green card holder) with 5 continuous years of US residence, and even then must pay full monthly premiums rather than getting it free.
Waiting period: Medicaid: most lawfully present immigrants face a 5-year bar after obtaining qualifying immigration status before they can enrol (federal minimum; some state exceptions exist). Medicare: a non-citizen without 40 US work quarters must first hold lawful permanent resident status for 5 continuous years before they can even buy into Part A/B by paying premiums, in addition to reaching age 65.
If you are retiring here
A UK retiree who moves to the US late in life with no US work history and no US-working spouse cannot access Medicare in any form until they have held a green card (lawful permanent residence) for 5 continuous years, and even then must pay a full monthly Part A premium (reported as roughly USD 565/month for those with fewer than 30 quarters, or a reduced roughly USD 311/month for 30-39 quarters, plus the standard Part B premium of roughly USD 202.90/month) rather than getting it free; in practice such a retiree needs to rely entirely on private international or US health insurance, which becomes expensive at older ages and may exclude pre-existing conditions.
What public cover will not give you
- No public insurance option exists at all for anyone under 65 who is not disabled or Medicaid-eligible, and most immigrants are barred from Medicaid for 5 years regardless of income
- Employer coverage is tied to the job and lost on redundancy (COBRA continuation exists but is expensive and time-limited)
- ACA marketplace premium tax credits are being narrowed for many lawfully-present immigration statuses starting 2026, with a further narrowing from 2027
- High out-of-pocket costs (deductibles, coinsurance, balance billing) even with insurance in place
- Pre-65 Medicare access does not exist under any circumstance, regardless of medical need
So do you need private health insurance?
Private (or employer-sponsored) health insurance is not legally mandated at federal level (the ACA individual-mandate penalty was zeroed out in 2019) but is de facto essential: without it, a resident is exposed to the full, uncapped cost of US medical care, where a single hospitalisation can run into tens of thousands of dollars.
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General information, not insurance, immigration or medical advice. Rules change and individual situations differ; check the official position before you commit. Researched from official sources, July 2026.