Neb. Rev. Stat. § 14-558

It shall be the duty of the city treasurer of a city of the metropolitan class to proceed as soon as practicable after any personal tax becomes delinquent, or prior to such delinquency whenever the city treasurer shall believe that any person, firm, or corporation is about to dispose of any personal property on which a tax has been levied, to collect such delinquent taxes by sale of the personal property of such person, firm, or corporation if any such property can be found within such city. No demand of taxes shall be necessary, but it shall be the duty of every person owing any municipal tax or taxes in such cities to pay such taxes at the city treasurer's office.