New Jersey Statutes Title 40A. Municipalities and Counties 40A § 7-3

The county to which part of the territory of another county is annexed shall be liable to pay such proportionate part of the indebtedness of the county from which the annexed territory is taken, as the value of the property assessed for the purpose of taxation in the annexed territory bears to the entire amount of property assessed for that purpose in the county, according to the assessments for the purpose of taxation made by the appropriate taxing officers of the several taxing districts of the county in the year preceding the annexation.