As recently reported,  new U.S. legislation has been pending in Congress that would permit  the revocation or denial of U.S. passports in the case of unpaid taxes in excess of $50,000.  

On December 3rd, H.R. 22, Surface Transportation Reauthorization and Reform Act of 2015, a highway-funding bill in which the pertinent provisions are buried, was passed by the House of Representatives by a vote of 359 - 65, and then  by the Senate later that day by a vote of 83 – 16.

It has now been  presented to the President and he is expected to sign it into law.