What are the tax consequences of accepting and paying a debt relief offer?

First of all, we aren’t tax professionals and can’t give you tax advice. We recommend consulting a CPA or other qualified tax professional for individualized advice and guidance.

In general, a debt relief offer may cause you to owe taxes on some or all of the amount forgiven by your creditor (your savings). The forgiven amount of debt may be counted as income and subject to taxation. 

See also:
IRS Topic on Canceled Debt 
Tax Consequences of Settling a Debt from Nolo.com