If you have income from different countries, tax is levied on that income by multiple countries. If you have capital in another country than that in which you reside, you will also be confronted with this issue. If tax is levied on the same income or capital by more than 1 country, this is called double taxation.
To avoid that you pay tax on your income or your capital more than once, the Netherlands has concluded tax treaties with a considerable number of countries. A tax treaty is an agreement between 2 countries about which of them has the right to levy tax on certain income. The contents of the treaties are not the same for every country. To know what the exact consequences are for your tax levy in the Netherlands, you must read that treaty.
If the Netherlands has not concluded a tax treaty with the country concerned, the 'Double Taxation (Avoidance) Decree (2001)' applies. Application of this Decree will also result in the avoidance of double taxation. For more information about the avoidance of double tax, please see the double tax relief.