The Dutch government needs a source of revenue to provide residents with education, security and health care, as well as social security, motorways and railways, etc. Private individuals and businesses pay taxes and premiums in exchange for these services. The Belastingdienst collects these taxes and premiums, and ensures that anyone liable for tax adheres to the rules.
Dutch Customs [Dutch: Douane] is also a part of the Belastingdienst. The Douane monitors the import, export and transit of goods into, out of and through the Netherlands respectively.