Neb. Rev. Stat. §§ 77-1902
When land has been sold for delinquent taxes and a tax sale certificate or tax deed has been issued, the holder of such tax sale certificate or tax deed may, instead of demanding a deed or, if a deed has been issued, by surrendering the same in court, proceed in the district court of the county in which the land is situated to foreclose the lien for taxes represented by the tax sale certificate or tax deed and all subsequent tax liens thereon, excluding any lien on real estate for special assessments levied by any sanitary and improvement district which special assessments have not been previously offered for sale by the county treasurer, in the same manner and with like effect as in the foreclosure of a real estate mortgage, except as otherwise specifically provided by sections 77-1903 to 77-1917. Such action shall only be brought within nine months after the expiration of three years from the date of sale of any real estate for taxes or special assessments.
Neb. Rev. Stat. §§ 77-1902