Neb. Rev. Stat. §§ 77-1843
In all controversies and suits involving the title to real property claimed and held under and by virtue of a deed made substantially by the treasurer in the manner provided by sections 77-1831 to 77-1842, the person claiming the title adverse to the title conveyed by such deed shall be required to prove, in order to defeat the title, either (1) that the real property was not subject to taxation for the years or year named in the deed; (2) that the taxes had been paid before the sale; (3) that the property has been redeemed from the sale according to the provisions of sections 77-1201 to 77-1219, 77-1229 to 77-1236, 77-1301 to 77-1318.01, 77-1501 to 77-1514, 77-1601 to 77-1618, 77-1701 to 77-1710, 77-1716 to 77-1738, 77-1740 to 77-1767, and 77-1801 to 77-1855, and that such redemption was had or made for the use and benefit of persons having the right of redemption under the laws of this state; or (4) that there had been an entire omission to list or assess the property, or to levy the taxes, or to sell the property.
Neb. Rev. Stat. §§ 77-1843