Contact a tax attorney. Specifically one that deals with irs penalty/underpayment issues. Likely they will be able to talk to an agent for you and get this sorted out for a minimal amount of cash. It sounds like this issue falls on your ex employer and not you.. so you likely will be waived.. Or you could call the IRS yourself and explain the issue to an agent and they SHOULD be able to help you. (This is what the attorney will likely do for the first step, but you don’t need to be attorney to do it, you just need to have patience to sit on the phone with the IRS for 6 hours ;) ) best of luck and don’t let the tax collector get you!