ARM 42.2.505. INTEREST ON UNPAID TAX

(1) Interest on unpaid tax must be calculated as set forth in 15-1-216, MCA. (2) In the case where there is unpaid tax for a year that is reduced by the carryback of a subsequent year's net operating loss, interest on the unpaid tax accrues to the later of: (a) the due date of the loss year return; or (b) the date the loss year return is actually filed. This limited interest calculation applies only to the unpaid tax offset by the net operating loss carryback.