N.J. Stat. § 43:10-57
A fund shall be created in the following manner for the purpose of paying such pensions, to wit: There shall be deducted from every payment of salary to each county probation officer three per centum (3%) of the amount thereof, then there shall be contributed annually by the county an amount equivalent to three per centum (3%) of such probation officers' salaries; to such sum there shall be added all moneys donated for the purpose of such fund, and all rewards which may be paid to any county probation officer while acting as such county probation officer, all of which moneys and rewards shall be paid over to the board of chosen freeholders of the county to be deposited in such fund. In case, at any time, there shall not be sufficient money in such pension fund to pay such pensions, the board of chosen freeholders of the county shall, from time to time, include in any tax levy a sum sufficient to meet the requirements of such pension fund. Whenever such pension fund shall exceed an amount which the board of chosen freeholders of such county shall by resolution from time to time determine to be adequate for such pension fund, no moneys, except the three per centum (3%) specified in this article, and the moneys given or donated as herein mentioned and any aforementioned rewards, shall be paid into such fund, unless and until the amount of such fund shall fall below the amount thus determined to be adequate. Any county probation officer who has paid into the pension fund for at least four years, and is no longer in the service, shall have the right to withdraw from such pension fund and shall be entitled to a refund of the moneys theretofore deducted from his salary. All pensions granted under this article shall be exempt from any State or municipal tax, levy and sale, garnishment or attachment, or any other process whatsoever, and shall be unassignable.
N.J.S. § 43:10-57