Form 1099-C is a tax document for the Cancellation of Debt.
If your creditor agrees to cancel or forgive some or all of your debt, the U.S. Internal Revenue Service considers this income. Creditors and debt collectors who agree to accept at least $600 less than the original balance are required to file 1099-C forms with the IRS and to send you a notice of this filing. You must report that portion of forgiven debt as "income" on your federal income tax returns.
If you have received a 1099-C “Cancellation of Debt,” do not ignore it. Take the notice to a tax advisor. Even if you don’t have to pay the tax, you still need to file a form with the IRS.