Neb. Rev. Stat. § 18-1221

Subject to the levy limitations contained in section 77-3442 , but notwithstanding any limitations in any other law or city home rule charter, any city or village of this state which provides a pension or retirement system for all or a portion of its employees shall levy a tax in addition to all other taxes in order to defray the cost to such city or village in meeting the obligations arising by reason of providing such pension or retirement system. The revenue so raised shall be limited to the amount required to defray the cost to such city or village in meeting the obligations arising by reason of providing such pension or retirement system, and shall be used for no other purpose.