The IRS does not report to the credit bureaus, however, a tax lien filed against a taxpayer's social security number is public information. All that is needed is to walk into your local county courthouse and give the person's name to get a copy of the tax lien (form 668Y).
Once the Lien is filed, hence, made public, the credit bureaus pick up the information from the appropriate public records office (county recorder, MENSE, Secretary of State (UCC) or US District Court) and report accordingly.
A tax lien can affect your credit ratings negatively by lowering your score by as much as 200 points. In order to minimize the chances of a tax lien being filed against your social security, it is imperative that all returns be filed and an agreement be reached with the IRS to resolve your tax liability.
Be sure to consult with a competent and reputable tax consultant for the best possible outcome.