Comment by PopAlongKid
3 hours ago
>mis-filed my taxes a couple years ago, which cost me about $20K
What do you mean by "cost you $20K"? That your tax liability was calculated by the accountant to be higher than it actually should have been? Or that the accountant calculated your liability too low, which was caught and billed by the IRS?
In the first case, you can still file for a refund within 3 years (I'm omitting some technical details), but in the latter case, as mentioned by others, you still owe the tax whether it was correctly reported on your original return or not.
Years ago I had a similar issue. Accountant did something incorrect, increasing my liability by around $50k. Tax date came so I paid it, but moved accountants. New person fixed the issues, refiled, but it took a long time to get the refund back. IIRC, the IRS did include some nominal interest for the time they had the money.