Mont. Code Ann. § 23-2-809

If a decal required in 23-2-804 indicating that the off-highway vehicle fee has been paid is lost, mutilated, or becomes illegible, the person to whom it was issued shall immediately apply for and obtain a duplicate decal upon payment of a fee of $5 to the county treasurer, who shall forward the fee to the state, as provided in 15-1-504, for deposit in the state general fund.