You will need to amend your tax return to show the 1099-C since the IRS will be receiving a copy of it as well.
Amending is done on Form 1040X. Amended returns have to be printed and filed by mail. It
can take the IRS up to 12 weeks or longer to process them. If you are
due a larger refund than on your original return, your amended return should
only show the difference and you will receive a separate check for it. If
you owe money on your amended return, it will show only the new amount owed,
you will have to mail a check with the return.
How to Amend?
https://ttlc.intuit.com/replies/3288565
Form 1099-C
Normally, cancellation of debt is taxable income. However,
there may be some exceptions due to insolvency or other situations. A tax
professional will be able to take the time to review the options for your
particular situation.
Here are the links to those IRS Publications if you want to read
about Cancellation of Debt in relation to taxes.
IRS - Publication 4681 - Cancelled Debts,
Foreclosure, Repossessions, and Abandonments
IRS Publication 544 (2015), Sales and
Other Dispositions of Assets
