Imagine this situation. No sooner did you put all the finishing touches on your 2009 tax return and e-filed it, you discovered some new information. Perhaps an extra W-2 or 1099 comes in the mail. Or perhaps, a brokerage firm or employer sends you a corrected W-2 or 1099. Or maybe you just find some extra deductions.
You can revise a previously filed tax return. It's called filing an amended return. When should you file it? Technically an amended return can be filed anytime after an original return has been filed and accepted by the IRS. If you only recently submitted your return via e-file, wait to see if the IRS servers accept or reject your return.
If your e-file was rejected, that will actually be good news. You won't have to go through the longer process of amending your return. Instead make any corrections to your original tax return (including fixing any errors identified by the IRS computers), and re-submit your tax return.
If your return has been accepted, then you will need to prepare an amended return. Doing this by software is fairly easy. Your software should provide you with a menu option to amend the return. You'll then make any changes, and the software will print out the necessary forms.
I would wait at least a little while before sending in the amended return. (Amended returns have to be mailed in for manual processing by the IRS.) Here's why I think waiting is a good idea. First, it gives you time to see if any more documents or correction notices arrive in the mail. Second, it gives you time to think about other deductions or credits. Waiting a couple weeks or a month won't hurt, and could give you added reassurance that you've covered all your bases.