N.J. Stat. Ann. § 54:50-3

The commissioner or any employee of the state tax department by him thereunto designated, may conduct hearings, administer oaths to, and examine under oath, any taxpayer and the directors, officers, agents and employees of any taxpayer and as well all other witnesses, relative to the business of such taxpayer in respect to any matter incident to the administration of this subtitle, or any state tax law.