I still use a CPA but check his work using Claude. A CPA's mistake costs you less than your own LLM's mistake, because the CPA is liable for theirs.
Yes, you are, in the end, responsible for your own taxes the filings. If a mistake was made and you owe additional taxes, you have to pay them as well as any penalties, etc. But if you used a CPA, you have the option to sue to recover any loss they caused you through negligence.