Claimed to be Mr. Johnson from IRS auditing department. Stating that he has found there are insufficient reported tax on the return and requested the owner to call back ASAP.
There is a widespread IRS or "tax scam" being practiced by scammers on both Canadian and USA residents.
USA tax payers should read this:
http://www.irs.gov/uac/Newsroom/IRS-Reiterate ... -Telephone-Scam
Short answer:
The IRS never initiates a contact via phone.
They always send a snailmail first.
Educational post:
This scam is also described as scam #11, here:
http://phonehelp.2truth.com/facts.html
If you were contacted by an IRS impostor, you may file a report, after clicking on this link:
http://www.treasury.gov/tigta/contact_report_scam.shtml