As full-time travelers, Kristy Shen and Bryce Leung, a 30-something married couple from Toronto, are covered through what’s known as expat insurance. They recently purchased a policy from IM Global with a $2,500 deductible for around $30 each per month, Mr. Leung said. For dental work, they practice medical tourism. “We got our teeth cleaned in Poland for about $50,” Ms. Shen said, adding that she found their dentist on the site Dental Departures.

Carl Jensen, a software engineer near Denver who “fired” last year, at first bought coverage from the Affordable Care Act exchange, paying around $700 per month for his family of four.

The family now has coverage through his wife’s employer (she took a job after he retired). Should they need to self-insure in the future, Mr. Jensen would likely use a health care cooperative like Liberty HealthShare, as other FIRE adherents have, where members share medical expenses. A policy for his family would cost about $500 per month, he said.

While health care is expensive in the United States, some of it nevertheless operates on a sliding scale, said Pete Adeney, a.k.a., Mr. Money Mustache. For instance, A.C.A. plans are subsidized.

“So, if you are truly retired with, say, a $1 million portfolio and choosing to live off $25,000 of annual dividends, that is your only taxable income, and you would qualify for very low health insurance premiums,” Mr. Adeney said.