N.J. Stat. § 40:3-18: When contributions to cease

When the sinking fund of any issue of term bonds shall equal the amount of the uncanceled bonds of such issue, no further contributions shall be required to be made thereto, except to make good any losses which may occur, and the earnings of such sinking fund may be used to reduce the total annual sinking fund requirements, as provided in section 40:3-16 of this title.