HI -- I mailed my I-751 form on September 4, 2007 and I just realized that I mailed an expired form and the wrong amount. They issued an new form on 7/30/07 but I was too studid to double check the money amount and so mailed a check for $275 instead of $545. I can't believe I did this

Should I send a new application with the new amount or should I wait until I hear back from them? I have a VERY important trip planned for the first week of December and I'm afraid I won't get my Notice in time to travel.

Your advice is needed and appreciated!!

what will happen is that the whole application will come back to you. you will have to submit it again... unfortunately... they will probably accept the form, but if the amount is wrong you will have trouble. You may want to double check on your trip to see what is required.