Mont. Code Ann. § 15-70-108 — Payment Of Taxes By Negotiable Instrument

15-70-108 . Payment of taxes by negotiable instrument. The department of transportation is not bound by conditions pertaining to endorsement by the department that are placed on a negotiable instrument by the maker or drawer, tendered to the department for the payment of a tax liability or other liabilities, unless:
(1) the debtor and the department have previously entered into a written agreement that specifies the amount of the debtor's liability; and
(2) the amount tendered is in accordance with the written agreement.