Neb. Rev. Stat. § 77-27,128

The review provided by section 77-27,127 shall be the exclusive remedy available to any taxpayer for the review of the action in respect to the assessment of a proposed deficiency. No injunction or other legal or equitable process shall issue in any suit, action, or proceeding in any court against this state or against any office of this state to prevent or enjoin the assessment or collection of any tax imposed under the provisions of the Nebraska Revenue Act of 1967.