Mont. Code Ann. § 15-1-231 — Payment Of Taxes By Credit Card And Other Commercially Acceptable Means

15-1-231 . Payment of taxes by credit card and other commercially acceptable means. (1) The department may accept payment of any tax that it administers, including penalties, interest, and fees, by credit card, debit card, or other commercially acceptable means.
(2) (a) If the payment is made by credit card, debit card, charge card, or similar method, the tax liability is not discharged and the person has not paid the tax until the department receives payment or credit from the financial institution or credit card company responsible for making the payment or credit and the payment or credit is not subsequently charged back to the state by the financial institution or credit card company. Upon receipt of the payment or credit, the amount is considered paid on the date on which the charge was made by the taxpayer, unless the payment or credit is subsequently charged back to the state by the financial institution or credit card company.
(b) Upon notice of nonpayment, the department may charge the person who attempted the payment of the tax a fee not to exceed the costs of processing the claim for payment of the tax. The amount of the fee must be added to the tax due and is collected in the same manner as the tax due.
(3) The taxpayer shall pay all fees required by a financial institution or credit card company for a payment made pursuant to this section.