Neb. Rev. Stat. § 9-1206

If the tax provided for in section 9-1203 is not paid within such time as provided in section 9-1205 or as may be prescribed for payment thereof by rules and regulations prescribed by the commission, the same shall become delinquent and a penalty of ten percent shall be added thereto, together with interest at the rate specified in section 45-104.02 , as such rate may from time to time be adjusted, until paid.