Each jurisdiction has its own rules for defining tax residence. Normally an individual is tax resident in the country where they live and spend most of their time each year. However, some countries (e.g. the United States) may also treat an individual as resident for taxation based on their nationality or citizenship. Because tax residence is determined by the country or countries in which tax is paid, it is possible to be tax resident in more than one country at the same time.
An entity’s tax residency is usually where it is established or conducts most of its activity.