1:00 AM

BY STEPHEN OHLEMACHER, Associated Press

WASHINGTON -- The Supreme Court's decision to uphold most of President Barack Obama's health care law will come home to roost for most taxpayers in about 2 1/2 years, when they'll have to start providing proof on their tax returns that they have health insurance.

That scenario puts the Internal Revenue Service at the center of the debate, renewing questions about whether the agency is capable of policing the health care decisions of millions of people in the United States while also collecting the taxes needed to run the federal government.

Under the law, the IRS will provide tax breaks and incentives to help pay for health insurance and impose penalties on some people who don't buy coverage and on some businesses that don't offer it to employees.

The changes will require new regulations, forms and publications, new computer programs and a big new outreach program to explain it all to taxpayers and tax professionals. Businesses that don't claim an exemption will have to prove they offer health insurance to employees.

The health care law "includes the largest set of tax law changes in more than 20 years," according to the Treasury inspector general who oversees the IRS. The agency will have to hire thousands of workers to manage it, requiring significant budget increases that already are being targeted by congressional Republicans determined to dismantle the president's signature initiative.

"Knowing the complexity of the health law, there's no question that the IRS is going to struggle with this," said Rep. Charles Boustany Jr., R-La., chairman of the House Ways and Means oversight subcommittee. "The IRS wants more resources. Well, we need to start digging down into what are they doing with the resources and personnel."

Treasury spokeswoman Sabrina Siddiqui said, "The overwhelming majority of funds used by the agency to implement the Affordable Care Act go to administer the premium tax credits, which will be a tax cut averaging about $4,000 for more than 20 million middle-class people and families."

The Supreme Court, in its 5-4 ruling, upheld the mandate that most Americans get health insurance. The majority said Congress has the power to enforce the mandate under its taxing authority. The decision labeled the penalties a tax, noting that they will be collected by the IRS.

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Enforcing health care law to be a mammoth task