Senator Bernie Sanders’s health care plan is advancing a notion that has long been out of fashion in American politics: that the federal government should provide a new, expensive service to most Americans, and that it should levy significantly higher taxes on most Americans to provide that service.

He is proposing a health care plan that would require over a trillion dollars a year in new, broad-based taxes applying to nearly all Americans who work. His main opponent, Hillary Clinton, has reiterated President Barack Obama’s pledge not to raise taxes even on many affluent families, setting her cutoff for tax increases at $250,000.

His campaign estimates that his plan to cover all Americans with a zero-deductible, zero-co-pay health plan will add $1.38 trillion a year to government spending. There are reasons to think that estimate is optimistically low, but even if it’s correct it’s still a lot of money: Paying for it would require increasing federal tax receipts by about a third, and Mr. Sanders has a plan to do so.

According to revenue estimates provided by the campaign, $238 billion of his new revenues would come from taxes focused specifically on people making more than $250,000 a year or inheriting estates larger than $3.5 million.