The IRS does not need to sue anyone. They send you first class letters delivered by the Post Office. Several of them. Ignore those, and they then send certified letters that you need to sign for. Again delivered by the Post Office. Ignore those and they simply freeze your bank accounts and anything else you own. If they can do that, then why would they bother with a court case that might take them years before they get in front of a judge? They also do not bother arresting people for a few thousand dollars for the same reasons I have already given. The IRS does not accept payment in Itunes Cards, Amazon gift cards, or any other type of payment other than cash, check, credit or debit card (from normal everyday citizens).
Official IRS Government site detailing this scam and providing links to report it:
http://www.irs.gov/uac/Newsroom/IRS-Warns-of-Pervasive-Telephone-Scam
https://www.irs.gov/uac/Online-Scams-that-Impersonate-the-IRS
https://www.irs.gov/uac/Tax-Scams-Consumer-Alerts
https://www.irs.gov/uac/Newsroom/Phone-Scams- ... 6-Filing-Season
https://www.irs.gov/uac/Newsroom/IRS-Complete ... -Scams-for-2015
https://www.irs.gov/uac/irs-warns-taxpayers-o ... unes-gift-cards