Neb. Rev. Stat. §§ 66-1843
If any jurisdictional utility against which an assessment has been made pursuant to the State Natural Gas Regulation Act, within fifteen days after the notice of such assessment, (1) neglects or refuses to pay the same or (2) fails to file objections to the assessment with the commission as provided in section 66-1844, the commission shall transmit to the State Treasurer a certified copy of the notice of assessment, together with notice of neglect or refusal to pay the assessment, and on the same day the commission shall mail by registered mail to the utility against which the assessment has been made a copy of the notice which it has transmitted to the State Treasurer. If any such utility fails to pay such assessment to the State Treasurer within ten days after receipt of such notice and certified copy of such assessment, the assessment shall bear interest at the rate of fifteen percent per annum from and after the date on which the copy of the notice was mailed by registered mail to such utility.
Neb. Rev. Stat. §§ 66-1843