Among many other things, the law rescinded the old methodology by which the government paid Medicare Advantage providers and replaced it with a new one. The House spending bill would prohibit HHS from making payments under the new regime. And with the old regime eliminated, the department would have no legal authority to cover those services, according to Sebelius.
"This would seem to mean that payments to [Medicare Advantage] organizations would have to be suspended, risking a significant disruption in services to beneficiaries enrolled in Medicare Advantage," Sebelius writes.
Even in cases where HHS has retained the authority outside of the health care law to make payments to various providers, they'd have to establish new rules and rates governing those payments -- a process that would take months. "While the new rates were implemented, CMS would be prohibited from paying providers and suppliers at the Affordable Care Act rates."
Under the House plan, HHS would also be prohibited from covering annual wellness visits for the elderly, and continuing other programs for early retirees and people with pre-exisitng conditions. President Obama's promised to veto H.R. 1, and Republican aides privately acknowledge that this provision won't survive bipartisan spending negotiations. But you can see they really thought this one through. Read the Baucus/Sebelius correspondence here.