Ask a Lawyer and Get Answers to Your Legal Questions
You are not liable for this IRS invoice.
However, it is going to be very important to be proactive in documenting your communications with the IRS, and ensure that you do not miss any appeals deadlines associated with the claim (review the documentation you receive carefully, and ask the agent(s) you speak with for any appeals information if necessary.
Hopefully they will be able to deal with this matter without going through the formal administrative appeals process (they should be able to do so).
Confirmation letters: Keep written records of all communications - so if you speak to someone by phone, promptly send a follow up "confirmation letter" summarizing your conversation, who you spoke to, when, and any agreements you reached. Keep copies of your outgoing correspondence, as well as anything that you receive.