As of this post, Congress has not acted to “patch” the AMT exemption amount for 2012. It is very likely that they will as stated here, but an adequate tax plan necessitates that you calculate your projected tax liability under the current law with no patch. That way you can decide whether or not to pay in the additional tax that would be due with NO AMT patch in order to avoid interest and tax penalties when you file your 2012 tax return.
Your employer is very likely not including the AMT in your withholding and it is also likely that if you are paying estimated taxes you are not accounting for the AMT. If you would like to see what your potential tax liability is under both circumstances, please contact my office.