Idaho Statutes Title 63. Revenue and Taxation § 63-3032. Time for filing income tax returns

(a) Returns made on the basis of the calendar year shall be filed in the office of the Idaho state tax commission on or before the fifteenth day of April following the close of the calendar year and returns made on the basis of a fiscal year shall be filed in the office of the Idaho state tax commission on or before the fifteenth day of the fourth month following the close of the fiscal year.

(b) In the case of a return for any period of less than one (1) year, the return shall be filed on or before the date required in this section, or on or before such date as required for such tax period by the Internal Revenue Code, whichever is later.