My wife and I each have been employed until December 2009. In Dec 2009 she started her own business and is no longer employed. In the same month, I went from running my own business part time to running it full time. 1. Do we file two Schedule C/C-EZs with our one joint-married 1040 return? 2. When do we start paying quarterly taxes? I think neither of us has to make estimated tax payments this coming Jan 2010, April 2010, June 2010, Sept 2010 -- won't need to until Jan. 2011 - because: * Both of us were employed thru all but 1 month of 2009, and employers withheld taxes. * Taxes are paid in current year for the previous year. I will have paid my taxes for all of 2009 on April 15 anyway. Do I need to file for both of us in January (next month)? Is this correct? If not, when and how should we be filing?