HEALTH CARE COVERAGE NOW MANDATORY IN MASS.

There is a lot of talk about overhauling health care in the United States, but Massachusetts is actually trying to do it - again.

Today, it becomes the first state in the nation to require its 6.5-million residents to have health insurance or face financial penalties.

Making insurance mandatory - and more affordable - is the centerpiece of a law approved by the Legislature last year that civic and business leaders hope will dramatically reduce the ranks of the state's 400,000 uninsured.

Nearly 20 years ago, then-Gov. Michael Dukakis signed legislation that was supposed to bring coverage to everyone by 1992. But its requirement that employers provide coverage to workers or pay a tax was unpopular, and it was never implemented.

Still, Massachusetts's new grand experiment could become a model for major changes in health care across the country - if it works.

Their place in the national spotlight is not lost on the state officials, business leaders and consumer advocates who forged an unlikely alliance to get the law passed in April of last year.

"They might like to imitate us, some of them, but a lot of them can't wait for us to fail," said Jon Kingsdale, executive director of the Commonwealth Health Insurance Connector Authority, the new state entity implementing the law. "It's actually very helpful pressure, because people in Massachusetts feel the pressure of the national eyes on us, so they are particularly concerned that this not fail."

When Massachusetts residents file their state tax returns next spring, they must certify that they had acceptable health insurance coverage as of the end of 2007 - or lose a $219 personal tax exemption. The penalty grows steeper in subsequent years, big enough, officials hope, to persuade most holdouts to get coverage.

The state's 175,000 employers have to pitch in. Businesses with 11 or more full-time employees that do not offer insurance must pay an annual "fair share" assessment of $295 per employee.

The government is defining basic coverage and trying to make insurance more affordable. Under its new Commonwealth Care program, it is subsidizing coverage on a sliding scale for people with incomes of up to 300 percent of the federal poverty level, or $61,950 for a family of four. About 130,000 low-income people are already enrolled either in Commonwealth Care or MassHealth, the state's Medicaid program, state figures show. The poorest pay no premiums.