I going to very careful in my answer due to possible legal issues: A 1099C is issued by a lender when a loan is deemed uncollectible and written off. Although case law has varied and usually favored the lender, my understanding today is that once a 1099C is issued further collection efforts are canceled as is the obligation of the debt. As far as federal/state tax obligation(s), the amount listed on a 1099C is considered for tax purposes as ordinary income with a big loophole for the taxpayer, that being if you are considered insolvent at the time the1099C is issued the tax obligations are waived (forgiven).
https://www.irs.gov/forms-pubs/about-publication-4681
https://www.communitytax.com/cancellation-debt-questions-answers-1099-c/
Now as far as the situation you spoke about you can file a revised tax return or you can test your luck and just wait to see if the IRS contacts you with a "tax adjustment with added interest" - which may or may not happen based on personal experience. Should you roll the dice and wait for an IRS notice (and your state will probably follow but not lead) you can at that time file for a waiver due to insolvency if that is the case.
I caution you that I am not an attorney and this information is based on my personal experiences. Whether or not the disability status helps to document low income or not, I can't say unless its SSI (may or may not if its SSDI since SSDI doesn't really limit assets), but one could make the case for insolvency if a disability income is ones' only income or assets.
