that is, if repugs fail to get their acts together, tax cuts will expire January 1, and hopefully repugs will feel pressure from their constituents. If nothing is done until after inaugural and next Congress, there's another chance.
If/when agreement is arrived at after Jan. 1, measures in the agreement can be made retroactive.
IF no agreement for long enough period of time, adverse effects of tax increases and 'sequestration' will be felt on economy. After that,