Involves individual users residing in higher tax jurisdictions purchasing products in nearby lowertax jurisdictions for their own consumption within the customs constraints. This can involve crossing national borders, particularly where such border crossing is freely or relatively easily done (as between the European Union Member States) or can take place within a given country where there are significant differences in subnational taxes (as in Canada where provincial taxes differ, or in the United States where state and local taxes can vary considerably across jurisdictions). Within some countries, this also involves purchases from shops located in tax-exempt areas, such as Aboriginal reserves in Canada and Native American reservations in the USA. In some cases, there are limits on how much can be purchased outside of the jurisdiction in which the individual resides (e.g. the European Union), while in others the individual is supposed to pay the difference between the tax in their home jurisdiction and the tax they have paid on the products purchased in other jurisdictions (e.g. in various US states). However, enforcement of these provisions is difficult.