I myself have not seen anything of this nature (at least not yet). It is common for phishers to try and imitate legitimate organizations, especially during popular events (such as major holidays and national events).
Relating specifically to the IRS, US government entities are the only people in the world who can have a .gov domain name (i.e. www.irs.gov). So if you are contacted by someone who claims to be a government representative, you can use this as a red flag (look for jdoe@irs.gov).
There are a number of things you can do investigate the legitimacy of an email. Below is a short list ideas.
1. Never reply to an unrequested email with any valuable information. No matter who it appears to from.
2. Remember that email sources can be faked. Try investigating the message headers to help see if the sender is try to disguise the real sender.
3. Go to the website of the sender and make an assessment of whether or not this is a legitimate organization.
4. Make phone call to the presumed sender to help establish legitimacy of the person and/or organization.
I could go on an on with ideas, but it just comes down to using the same amount of critical thinking and discrimination you do when you receive a phone from someone you don't know or a stranger on the street.
