Ark. Code Ann. § 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.