Mont. Code Ann. § 15-1-405 — Injunction Not To Be Used To Restrain Enforcement Of Tax

15-1-405 . Injunction not to be used to restrain enforcement of tax. No injunction must be granted by any court or judge to restrain the collection of any tax or any part thereof or to restrain the sale of any property for the nonpayment of taxes except:
(1) where the tax or the part thereof sought to be enjoined is illegal or is not authorized by law. If the payment of a part of a tax is sought to be enjoined, the other part must be paid before an action can be commenced.
(2) where the property is exempt from taxation.