N.J. Stat. § 54:4-23.8
When land which is in agricultural or horticultural use and is being valued, assessed and taxed under the provisions of P.L. 1964, c.48 (C.54:4-23.1 et seq.), is applied to a use other than agricultural or horticultural, it shall be subject to additional taxes, hereinafter referred to as roll-back taxes, in an amount equal to the difference, if any, between the taxes paid or payable on the basis of the valuation and the assessment authorized hereunder and the taxes that would have been paid or payable had the land been valued, assessed and taxed as other land in the taxing district, in the current tax year (the year of change in use) and in such of the two tax years immediately preceding, in which the land was valued, assessed and taxed as herein provided.
If the tax year in which a change in use of the land occurs, the land was not valued, assessed and taxed under P.L. 1964, c.48 (C.54:4-23.1 et seq.), then such land shall be subject to roll-back taxes for such of the two tax years, immediately preceding, in which the land was valued, assessed and taxed hereunder.
Notwithstanding the provisions of any law, rule, or regulation to the contrary, land which is valued, assessed and taxed under the provisions of P.L. 1964, c.48 (C.54:4-23.1 et seq.) and is acquired by the State, a local government unit, a qualifying tax exempt nonprofit organization, or the Palisades Interstate Park Commission for recreation and conservation purposes shall not be subject to roll-back taxes. As used in this section, "acquired," "local government unit," "qualifying tax exempt nonprofit organization," and "recreation and conservation purposes" mean the same as those terms are defined pursuant to section 3 of P.L. 1999, c. 152(C.13:8C-3).
In determining the amounts of the roll-back taxes chargeable on land which has undergone a change in use, the assessor shall for each of the roll-back tax years involved, ascertain:
N.J.S. § 54:4-23.8