For several years now, people have been receiving phone calls from those claiming to be with the IRS. There are generally threats in regard to being delinquent in payments to the IRS and that they are coming to your house with the local sheriff, etc.
The IRS DOES NOT simply threaten you without notification! They have procedures in place which consist of sending you repeated notices in regard to issues.
If you should receive a phone call of this nature, please contact the IRS!
Check out these articles on scams!