Okay, take a deep breath. It may have sounded very serious. The person on the phone was threatening all sorts of things in order for you to make an immediate payment over the phone. Stay calm. The IRS will NEVER treat you in such a manner. The following is from the IRS website:
Note that the IRS will never:
Please feel free to contact our offices if you are uncertain. NEVER give out information, or payment, over the phone.
Check out this great video, from the IRS, regarding tax scams.