How The Affordable Care Act Will Affect Mass.

While most states are bracing for the launch of the new insurance marketplaces under President Obama's health care law, Massachusetts officials said Monday they're confident of a smooth transition.

One reason for the relative calm is Massachusetts' unique history as the first state to create a marketplace to help uninsured residents connect with coverage.

The 2006 Massachusetts law, signed by former Gov. Mitt Romney, provided a blueprint for the 2010 Affordable Care Act signed by Obama.

"I think we're as ready as we can be," Gov. Deval Patrick told reporters outside his State House office.

Despite the similarities, there will be some changes because the state law and the federal law rolling out Tuesday aren't exactly the same.

Among the changes:

- The website for the state's marketplace, the Health Connector, will be relaunched Tuesday with updated information to reflect changes from the federal law;

- 150,000 individuals insured through the state's subsidized Commonwealth Care program will have to begin re-enrolling in updated subsidized health care plans;

- 100,000 individuals will be shifted from Commonwealth Care into the state's Medicaid program, known as MassHealth;

- 45,000 uninsured people will become eligible for MassHealth;

- some smaller employers and individuals could end up paying more for coverage while others will save money;

- those who are deemed able to afford insurance but refuse to buy it will start facing both a federal "individual mandate" and the existing state penalty, but that won't trigger a double penalty, with the higher penalty acting as a cap;

- officials say the state will reap an additional $400 million in higher federal reimbursement in the fiscal year that begins next July as a result of the federal law.

Massachusetts has taken some steps to help ease the changes.

Lawmakers this summer repealed a mandate requiring employers provide health insurance to workers or pay a penalty — in part because the federal law included its own mandate.

Under the federal law, firms with 50 or more employees face a mandate to offer insurance or risk fines from the government starting in 2015.