Mont. Code Ann. § 72-16-1004
Liability for tax -- interest on delinquent tax
72-16-1004 . Liability for tax -- interest on delinquent tax. The person liable for payment of the federal generation-skipping transfer tax is liable for the tax imposed under 72-16-1002 . If the tax imposed by 72-16-1002 is not paid within the time established in 72-16-1003 , the tax is delinquent and draws interest at the rate of 10% a year.