Neb. Rev. Stat. § 23-506: Neb. Rev. Stat. § 23-506

No contract shall be entered into by the county board for the erection of buildings to be paid for out of such fund until at least seventy percent of such levy has been collected and paid into the county treasury. After the completion of said building, if sufficient funds are not in the county treasury to finish paying for same, warrants may be issued to an amount not exceeding eighty-five percent of the levy yet uncollected.