Neb. Rev. Stat. § 79-873

An authorization for a deduction under section 79-872 shall be in writing, and the form to authorize shall also include a notice to the employee of his or her right to refuse authorization. The authorization shall continue in force until revoked in writing by the employee. The authorization may also authorize the professional or labor organization to certify annually the amount to be deducted from each employee's wages, and such certification shall bind the employee, the school district, and the organization.