Not to sound too harsh, but you did make a mistake. You took money that wasn't yours. You have an accountant now - did you have one then? Why didn't you ask them about it? We just LIVE for those things. They make our day. Really!

So now you owe the IRS $15k and don't have it. With a careful reconstruction of the facts, you might be able to get out of the penalties. As you said, you paid everything on time - it was the IRS who initiated the refund. But don't expect to get out of the interest. You've had the use of the money for the last two years.

But first of all, you need to get the main issue straightened out: What IS your correct tax liability for 1999? What caused the IRS to send you the refund? There must have been something on the return or some error in their processing that generated the refund. Get to the bottom of that issue as quickly as you can, then you can deal with how much you owe the IRS and how to pay it.