tax bill of $13,200 for cancellation of debt

[Mike]

I just received a tax bill for over $13,000 on friday. The paperwork stated that in 2006 there was a cancellation of debt and that I should have filed tax on this as income. I did not even know that this had happened until friday. I went through a divorce in 2001. At that time, I was sending money to my ex, unfortunatley, she was not making payments and when I found this out, I did not have the money to catch up on the payments. They forclosed on the property and eventually sold the house. I owed $65,000 on the property they sold it for about half. I was told my the credit bureau that it would be on the record for 10 years. Nothing was stated that I would have to pay tax on the balance, and that the debt would be cancelled in five years and tax would be owed. Also, My former spouse's name was on the loan. I do not understand why I am just now hearing about this, and why the ex- is not held partly responsible. Has anyone had any experinece such as this? If so, what did you do.