The Washington Post published an article on April 8, 2015 titled “In Dallas, the IRS says it can’t chase tax cheats who owe less than $1 million.”  Here is a section of the article (emphasis added):

If these taxpayers are delinquent on $900,000, for example, the IRS won’t go after them; budget reductions have forced the revenue collection staff to train its firepower on cheats who owe $1 million or more.

“I have to say, sorry, we can’t get that money,” said Richard Christian, supervisory revenue officer for the Dallas area.  “Nobody’s ever going to knock on their door.”

Amazing that the IRS would publically say something like this.  That being said, if you are in a hole with the IRS, your best option is to work with them to get them paid ASAP.  Avoiding the IRS is never a good idea.