Tax residency is determined under the domestic tax laws of each jurisdiction. There might be situations when a person qualifies as a tax resident of more than one jurisdiction. Therefore, they will be considered as a tax resident in more than one jurisdiction.
Often, a major determinant of an individual's status as a resident for income tax purposes is whether they are domiciled or maintain an abode and are "present" in the state for 183 days or more (half of the tax year).
Other evidence often considered in evaluating whether there has been a permanent change in domicile includes your location of employment, location of the school a family's children attend, memberships in country clubs, social or fraternal organizations.