The headline on the CBO's analysis of the GOP's repeal bill is "Repeal Could Add $230 billion to deficit by 2021." The analysis is a bit more complicated .
CBO’s responsibility to the Congress is to estimate the effects of proposals as written and not to forecast future legislation. However, current law now includes a number of policies that might be difficult to sustain over a long period of time. If those policies or other key aspects of the original legislation would have subsequently been modified or implemented incompletely, then the budgetary effects of repealing PPACA and the relevant provisions of the Reconciliation Act could be quite different—but CBO cannot forecast future changes in law or assume such changes in its estimates.
There is wiggle room here to say what Republicans are saying: The CBO's account of "Obamacare's" cost is not Gospel in the long run, because these programs always, always, always cost more than anticipated. At the same time, CBO estimates that only 83 percent of Americans would be covered if health care reform is repealed, to 94 percent who'll be covered if it's implemented. But the argument Democrats are making right now, and trying scorch Republicans with, is "you're about to blow up the deficit."