The IRS has issued Notice 2018-1, which states the procedures for denying or revoking passports for "seriously delinquent" tax debts.

For those who do not know about the Taxpayer Advocate Service (TAS), its an independent office within the IRS that helps taxpayers resolve their problems with the IRS. 

Nina Olson, is the head of the Taxpayer Advocate Service and she has published a great blog post regarding the IRS's new passport revocation program for seriously delinquent taxpayers.