The nonpartisan Congressional Budget Office (CBO) on Thursday laid out in substantial detail the costs of not dealing with the so-called “fiscal cliff.”

CBO had already estimated that going over the cliff would spark a recession, while simply voiding the tax and spending increases would add trillions to the debt. But the new study breaks down the costs and benefits of allowing various parts of the fiscal cliff to remain in place.

It finds that unemployment would rise from 7.9 to 9.1 percent by the end of 2013 if the nation went over the cliff.

The CBO warning comes as President Obama, Senate Democrats and House Republicans are girding for a huge negotiation over spending and tax policy in the coming lame-duck session of Congress.