I received a 1099 - Misc back in January from AmEx for a prize I won from them. I went quite a few rounds with them over the FMV on it but they wouldn't budge.

I considered putting in my own adjustment but then decided that it wasn't worth the extra scrutiny from the IRS (not that I've ever knowingly done something wrong on my taxes but I doubt if I have kept copied of my relevant tax documents for longer than the past two years). So I filed and paid the extra $156 in taxes. My tax return was accepted and I received a refund.

Well, I just got an e-mail from AmEx letting me know that because of all the consumer complaints they are sending out new 1099's with the lower prize values. My question is how do I go about getting the extra $156 that I therefore overpaid in taxes? Is it just a 1040X? Is filing this going to be tantamount to waiving a huge red flag that says "please audit me"?

“My question is how do I go about getting the extra $156 that I therefore overpaid in taxes?“ Is it just a 1040X?”--->As you discover an error/discrepancy after your return has been mailed, you need to amend your return;you need to do file an amended return as your your income, your deductions(maybe) or credits are incorrect. If you are filing to claim an additional refund, wait until you have received your original refund. You cannot file an amended return electronically. A claim for refund usually must be filed within 3 years of filing the original tax return. you have overpaid your taxes and are due a refund from the IRS on your amended return.

“ Is filing this going to be tantamount to waiving a huge red flag that says "please audit me"?”----> Filing an amended tax return does not, in and of itself, "red flag" you for an audit. However, the Internal Revenue Service notes that amended returns go through a screening process just like regular returns, which could result in an audit. Also, filing an amended return adds an extra layer of IRS scrutiny of your taxes.