Mont. Code Ann. § 28-1-1211
When offer may be conditional
28-1-1211 . When offer may be conditional. (1) An offer of performance must be free from any conditions that the creditor is not bound to perform.
(2) When a debtor is entitled to the performance of a condition precedent to or concurrent with performance on the debtor's part, the debtor may make the offer depend upon the due performance of the condition.