The Senate bill uses estimated Medicare savings to extend the solvency of Medicare. Then, it uses the same money to balance the budget. CBO says it can't do both.
The nonpartisan agency said the $246 billion it projected the legislation would save Medicare can’t both finance new programs and help pay future expenses for elderly covered under the federal program.
The estimated Medicare savings in the legislation overstate “the improvement in the government’s fiscal position,” the CBO said in the letter.
“The true increase in the ability to pay for future Medicare benefits or other programs would be a good deal smaller,” the budget office said.
Arguments that the Medicare savings would both extend Medicare’s solvency and help finance “new spending outside of Medicare would essentially double count a large share of those savings,” the CBO said.
http://www.bloomberg.com/apps/news?pid=20601087&sid=ackCRQU57HhY&pos=9Looks like they've been called on their accounting gimmickry.