WASHINGTON — Nearly 6 million Americans, most of them in the middle class, will face a tax penalty for not carrying medical coverage once President Obama’s health care overhaul law is fully in place, congressional budget analysts said Wednesday.
The new estimate amounts to an inconvenient fact for the administration, a reminder of what critics see as broken promises.
The numbers from the nonpartisan Congressional Budget Office are 50 percent higher than a previous projection by the same office in 2010, shortly after the law passed. The earlier estimate found 4 million people would be affected in 2016, when the penalty is fully in effect.
That’s still only a sliver of the population, given that more than 150 million people currently are covered by employer plans. Nonetheless, in his first campaign for the White House, Obama pledged not to raise taxes on individuals making less than $200,000 a year and couples making less than $250,000.
And the budget office analysis found that nearly 80 percent of those who will face the penalty would be making up to or less than five times the federal poverty level. Currently that would work out to $55,850 or less for an individual and $115,250 or less for a family of four.
Average penalty: about $1,200 in 2016.
‘‘The bad news and broken promises from Obamacare just keep piling up,’’ said Representative Dave Camp, Republican of Michigan, chairman of the House Ways and Means Committee, who wants to repeal the law.
Starting in 2014, virtually every legal US resident will be required to carry health insurance or face a tax penalty, with exemptions for financial hardship, religious objections, and certain other circumstances. Most people will not have to worry about the requirement because they already have coverage through employers, government programs such as Medicare, or by buying their own policies.
A spokeswoman for the Obama administration said 98 percent of Americans will not be affected by the tax penalty, and suggested that those who will be should face up to their civic responsibilities.
The Supreme Court upheld Obama’s law as constitutional in a 5-4 decision this summer, finding that the insurance mandate and the tax penalty enforcing it fall within the power of Congress to impose taxes. The penalty will be collected by the IRS, just like taxes.
The budget office said the penalty will raise $6.9 billion in 2016.
Also Wednesday, the Obama administration said monthly premiums for popular private insurance plans through Medicare are only inching up next year, allaying some fears of skeptical older voters on a closely watched election-year issue.
Republican Mitt Romney has warned that changes through Obama’s health care law would hobble programs such as Medicare Advantage, the private option that’s a thriving part of Medicare. But deputy Medicare administrator Jonathan Blum said such dire predictions have not proved to be true.
The program ‘‘is stronger than ever,’’ Blum told reporters. ‘‘Beneficiaries should expect the overall quality of care is improving. . . . Also, cost growth remains controlled.’’