Mont. Code Ann. § 15-1-406 — Declaratory Judgment

15-1-406 . Declaratory judgment. (1) An aggrieved taxpayer may bring a declaratory judgment action in the district court seeking a declaration that:
(a) an administrative rule or method or procedure of assessment or imposition of tax adopted or used by the department is illegal or improper; or
(b) a tax authorized by the state or one of its subdivisions was illegally or unlawfully imposed or exceeded the taxing authority of the entity imposing the tax.
(2) The action must be brought within 90 days of the date the notice of the tax due was sent to the taxpayer or, in the case of an assessment covered by the uniform dispute review procedure set forth in 15-1-211 , within 90 days of the date of the department director's final decision. The court shall consolidate all actions brought under subsection (1) that challenge the same tax. The decision of the court applies to all similarly situated taxpayers, except those taxpayers who are excluded under 15-1-407 .
(3) The taxes that are being challenged under this section must be paid under protest when due as a condition of continuing the action. Property taxes are paid under protest as provided in 15-1-402 . All other taxes administered by the department, except estate taxes, are paid under protest by filing timely claims for refund and by following the uniform dispute review procedures of 15-1-211 . Estate taxes are paid under protest by following the procedures set forth in Title 72.
(4) The remedy authorized by this section may not be used to challenge the:
(a) market value of property under a property tax unless the challenge is to the legality of a particular methodology that is being applied to similarly situated taxpayers; or
(b) legality of a tax other than a property tax or estate tax unless the review pursuant to 15-1-211 has been completed.
(5) The remedy authorized by this section is the exclusive method of obtaining a declaratory judgment concerning a tax authorized by the state or one of its subdivisions. The remedy authorized by this section supersedes the Uniform Declaratory Judgments Act established in Title 27, chapter 8. This section does not affect actions for declaratory judgments under 2-4-506 .