A boarding or rooming house containing fewer than eight units must be registered, and collect and remit sales tax on taxable occupancies as a hotel, unless it is held out by the operator and kept open for the residence of permanent boarders or lodgers. A permanent boarder or lodger is any person who occupies or has the right to occupy a room or rooms in the house for at least 90 consecutive days.
N.J. Admin. Code § 18:24-3.7