Section 26-51-402 - Tax year - Basis for determining liability(a) A taxpayer must calculate his or her Arkansas income tax liability using the same income year for Arkansas income tax purposes as used for federal income tax purposes.(b) A taxpayer must provide to the Secretary of the Department of Finance and Administration a copy of any certification or approval from the Internal Revenue Service authorizing the taxpayer to change his or her income year.Amended by Act 2019, No. 910,§ 3710, eff. 7/1/2019.Acts 1929, No. 118, Art. 3, § 9; Pope's Dig., § 14032; A.S.A. 1947, § 84-2012; Acts 1987, No. 382, § 12.