316 Neb. Admin. Code, ch. 22, § 017
Any person subject to tax under the Nebraska Revenue Act of 1967, as amended, or any person required to file an information return for the taxable year, shall keep such permanent books of account or records, including inventories and all supporting documents, as are sufficient to establish the amount of gross income, deductions, credits, or other matters which may be required to support any income tax or information return. Records of all fuel purchases must be retained if a credit for nonhighway use motor vehicle fuels was claimed.
Such books or records shall be kept available at all times for inspection by the Nebraska Department of Revenue or its agents for the purpose of ascertaining the correctness of any return or other document required to be filed under the Nebraska Revenue Act.
Each taxpayer shall retain all of his or her records relating to a taxable year as long as their contents may become material in the administration of any Nebraska tax laws. If the Nebraska Department of Revenue serves a notice of deficiency for a taxable year, the taxpayer shall retain all of his or her records relating to that taxable year until the deficiency has been satisfied, abated, settled, or disallowed.
316 Neb. Admin. Code, ch. 22, § 017