A 1099-C must be issued by a credit card company (and many other agencies and companies) if they cancel or forgive a debt of $600 or more.
That being said, I know a lot of required agencies and companies (including credit card companies) just don't issue them in the end.
Regardless, you are required to include any canceled or forgiven debt on your income taxes on the Other Income line, even if it is for less than $600, and even if no 1099-C was issued to you. Granted a lot of people don't follow the tax laws, but it is required that you do so. I strongly recommend following the tax laws, it just isn't worth taking the chance.
There are, however, times when you are allowed to exclude all or part of canceled debt. The debt needs to have been canceled through a bankruptcy, when the taxpayer is insolvent, or even when there is a good faith dispute over the amount owed.
Sounds like you probably aren't going through a bankruptcy. A good faith dispute over the amount owed would be extremely rare and hard to justify on a credit card (they always can provide records of your charges.) But, if you are insolvent, I would recommend reading the following wikipedia entry which I have written portions of to look into this exclusion further:
Cancellation of Debt (COD) Income - Wikipedia, the free encyclopedia
Also, if you try to exclude canceled debt from income, I recommend reading up at that link and consulting a tax adviser. It can be a bit complicated. (i.e. You have to make sure if you have any tax attributes that you reduce them.)
