Neb. Rev. Stat. § 19-4033

The total amount of special assessments or general business occupation taxes levied under the Business Improvement District Act shall not exceed the total costs and expenses of performing the authorized work. The levy of any additional assessment or tax shall not reduce or affect in any manner the assessments previously levied. The assessments or taxes levied must be for the purposes specified in the ordinances and the proceeds shall not be used for any other purpose.