Hi, I received a notice from the IRS saying that I didn't file a 1099c for a debt cancellation back in 2009. I DID include it, and I have it on my tax returns as proof. How do I tell the IRS that it was in fact included and I already paid the taxes on it?

Assuming that the amount from the 1099C line 2 is exactly the same as income you reported on line 21 of your 1040 ("Other Income"), then follow the appeal procedure. Make copies of your return and the 1099C, circle both entries, and attach an explanation describing that you included the amount. On your original tax return you should have given an explanation of this other income on line 21, such as writing in "canceled debt." If you actually reported a different amount on Line 21, then in your appeal provide detail as to how you came up with the number that you reported. And if you actually reported the amount somewhere other than line 21, then post back with details as to what happened, because you're going to have to write a detailed explanation to the IRS.

BTW - I assume that this debt foregiveness does not meet one of the exceptions for having to be included in your taxes - meaning this debt foregiveness was not for the mortgage on your home, and also you did not declare bankruptcy.