26 CAR § 100-120. Tax year — Basis for determining liability — Arkansas Code § 26-51-402

(a) Tax year — Calendar year versus fiscal year — Arkansas Code § 26-51-402(a). (b)(1) Taxable income is computed on the basis of a period of time called a tax year. (2) A tax year generally is the annual period on the basis of which the taxpayer regularly computes income in keeping its books and records. (3) The annual period is usually a calendar year or a fiscal year. (4) A calendar year is a period of twelve (12) months ending on December 31. (5) A fiscal year is a period of twelve (12) months ending on the last day of any month other than December. (c) A taxpayer must calculate income using the same tax year as that used on the federal income tax return. (d) A change of the tax year must be approved by the Internal Revenue Service, and a copy of the approval letter must be attached to the Arkansas income tax return.