Domicile is the place where a person or entity has its primary, permanent home or principal place of business. Domicile is important in the law for determining the state and county in which a person or entity may be sued, vote, and is obligated to pay taxes. For a person with multiple homes or different places of residence, domicile is the place the person plans to return to after being away, and may be indicated by the place where the person maintains important services and relationships, such as banking, driver’s license registration, incorporation, and work/employment. A person or entity is said to be a domiciliary of the domicile.

In Montana, domicile is defined as the place where an individual has their permanent home or principal establishment and to which, whenever they are absent, they intend to return. It is a significant legal concept because it determines jurisdiction for legal actions, voting rights, and tax obligations. For individuals with multiple residences, the domicile is typically the location where they have the most substantial connections, such as where they maintain a driver's license, where they bank, where they work, and where they have registered to vote. For entities, domicile is usually where the principal place of business is located or where the entity is incorporated. Establishing domicile in Montana involves demonstrating an intent to make the state one's permanent home, which can be evidenced by various factors including the address listed on legal documents, the location of family and social relationships, and the place where one's personal belongings are kept.