<p>Since you will have a significant difference in income between 2011 and 2012, I think you are better off using 2012’s numbers as it will give a more accurate picture and cause you less trouble down the road.</p>
<p>Unless you have a complicated tax situation, by November or December you should be able to pretty accurately predict all of your 2012 information. Most if not all tax programs have preview editions out by then that will have the correct tables and what-not.</p>
<p>If you are self-employed it gets trickier, but I would still try to estimate the 2012 numbers as closely as possible.</p>