Just a heads-up - be very suspicious of anyone calling and claiming to be from the IRS - they don't do that.
IRS Reiterates Warning of Pervasive Telephone Scam
I just got two calls in a row - both left the same pre-recorded message telling me that I needed to call them back before proceedings started. Yes, it's a threatening scam that is supposed to be scary.
The problem is that the IRS will never call you and leave a recorded message. They will always contact you through the mail - and it will be obviously authentic.