When is a tax treaty concluded?
The Netherlands has concluded a tax treaty with many countries to prevent you from paying tax more than once on your income or assets. All tax treaties can be found at rijksoverheid.nl.
A number of countries are also subject to a multilateral tax treaty (known as the ‘multilateral instrument’). This applies if both countries have agreed to it. The instrument replaces or amends certain parts of an existing treaty. More information on this is given at rijksoverheid.nl (Dutch only).
Has the Netherlands not concluded a tax treaty with a country?
And do you work in that country, or are you receiving benefits from that country? In that case, the 'Besluit voorkoming dubbele belasting 2001’ (Double Taxation (Avoidance) Decree 2001, Dutch only) applies.
The tax treaties do not contain any rules for the levying of national insurance contributions. Read more about this at Social security for cross-border working and entrepreneurship.