People who are economically active or reside in more than one country sometimes face complex tax rules. These persons must therefore check whether they are not subject to double taxation. Unless expressly excluded by an agreement, income from foreign sources is taxable in France. Residents are entitled to tax credits for WHT paid on certain types of income from other treaty countries. However, income from foreign sources exempt from French tax under a tax treaty is added to taxable income in France, either to determine the French tax rate for taxable income in France (exemption with progressivity) or to calculate the gross French tax debt from which the tax paid abroad is deducted (tax credit system), depending on the applicable tax treaty.