Mont. Code Ann. § 15-30-2609 — Credits And Refunds -- Period Of Limitations

15-30-2609 . Credits and refunds -- period of limitations. (1) If the department discovers from the examination of a return or upon a claim filed by a taxpayer or upon final judgment of a court that the amount of income tax collected is in excess of the amount due or that any penalty or interest was erroneously or illegally collected, the amount of the overpayment must be credited against any income tax, penalty, or interest then due from the taxpayer and the balance of the excess must be refunded to the taxpayer.
(2) (a) A refund or credit may not be allowed or paid with respect to the year for which a return is filed after expiration of the period provided by 15-30-2606 and 15-30-2607 or 1 year from the time the tax was paid, whichever is later, unless before the expiration of the period the taxpayer files a claim for refund or credit or the department has determined the existence of the overpayment and has approved the refund or credit.
(b) If an overpayment of tax results from a net operating loss carryback, the overpayment may be refunded or credited within the period that expires on the 15th day of the 40th month following the close of the tax year of the net operating loss if that period expires later than 3 years from the due date of the return for the year to which the net operating loss is carried back.
(c) Except for a final federal adjustment required to be reported for federal purposes by taking those adjustments into account in the partnership return for the year of the adjustment, a taxpayer may file a claim for refund or credit of tax on or before the later of:
(i) the expiration of the period provided for in subsection (2)(a); or
(ii) 1 year from the date a federal adjustments report described in 15-30-3403 and 15-30-3404 , was due to the department, including any extensions.
(3) Within 6 months after a claim for refund is filed, the department shall examine the claim and either approve or disapprove it. If the claim is approved, the credit or refund must be made to the taxpayer within 60 days after the claim is approved. If the claim is disallowed, the department shall notify the taxpayer and a review of the determination of the department may be pursued as provided in 15-1-211 .
(4) (a) Interest is allowed on overpayments at the same rate as charged on delinquent taxes as provided in 15-1-216 . Except as provided in subsection (4)(b), interest is payable from the due date of the return or from the date of the overpayment, whichever date is later, to the date the department approves refunding or crediting of the overpayment. With respect to tax paid by withholding or by estimated tax payments, the date of overpayment is the date on which the return for the tax year was due. Interest does not accrue on an overpayment if the taxpayer elects to have it applied to the taxpayer's estimated tax for the succeeding tax year. Interest does not accrue during any period for which the processing of a claim for refund is delayed more than 30 days by reason of failure of the taxpayer to furnish information requested by the department for the purpose of verifying the amount of the overpayment. Interest is not allowed if:
(i) the overpayment is refunded within 45 days from the date the return is due or the date the return is filed, whichever date is later;
(ii) the overpayment results from the carryback of a net operating loss; or
(iii) the amount of interest is less than $1.
(b) Subject to the provisions of subsection (4)(a)(i), if the return is filed after the time prescribed for filing in 15-30-2604 , including any extension, interest is payable from the date the return was filed.
(5) An overpayment not made incident to a bona fide and orderly discharge of an actual income tax liability or one reasonably assumed to be imposed by this law is not considered an overpayment with respect to which interest is allowable.