Taxes may be going up on wealthier Americans, but federal deficits could still exceed $9 trillion over the next decade after the enactment of the “fiscal cliff” legislation passed by Congress, according to a Congressional Budget Office report released Friday.

Assessments of the fiscal cliff deal’s deficit impact depend on the basis for comparison. Compared to what would have happened if no deal were struck, the deal increased deficits by about $4.6 trillion including interest payments. The reason is that it preserved most of the pre-existing tax rates that would have otherwise expired and increased spending, “mostly for refundable tax credits and unemployment compensation.” When compared with the tax and spending policies that were in place in 2012, the law cuts deficits by about $600 billion to $700 billion, the CBO estimated.

All told, deficits from 2013 through 2022 are now projected to be $6.9 trillion over the next decade under CBO’s basic baseline, up from $2.3 trillion in August. But under an alternative scenario that assumes, for instance, that Congress will continue to prevent Medicare physician payment cuts from going into effect, the total deficit could hit $9.2 trillion (or as the CBO puts it, about $700 billion to $800 billion lower than the roughly $10 trillion it estimated in August).

The CBO report underscores the challenge facing Obama in his second term. He’s reluctant to cut spending or agree to fundamental reforms to entitlements, but he won’t be able to significantly bring down deficits merely by raising taxes on wealthier Americans.