N.J. Stat. § 54:8A-17
From and after the first day of the first month following at least a full calendar month after the enactment of this act, every employer in this State of a taxpayer subject to tax in respect of wages, salaries or commissions derived from sources within this State shall deduct and withhold upon the same for each payroll period an amount computed in such manner as to result, as far as practicable, with due regard to the personal exemptions and standard deduction allowable under this act, in withholding during each calendar year a sum substantially equivalent to the amount of tax reasonably estimated to be due under this article. Methods for determining the amount to be withheld shall be prescribed by regulation, as shall procedures and requirements for the furnishing of written exemption certificates to the employer, the amending or substitution of the same, the furnishing by the employer of written statements showing the total compensation, the amount withheld and other specified information.
N.J.S. § 54:8A-17