|Observed by||Netherlands, Aruba, Curaçao, Sint Maarten|
|Date||15 December (if a Sunday, on Monday 16 December)|
|2014 date||15 December|
|2015 date||15 December|
|2016 date||15 December|
|2017 date||15 December|
Koninkrijksdag (Papiamento: Dia di Reino, English: Kingdom Day, Frisian: Keninkryksdei) is the commemoration of the signing of the Charter for the Kingdom of the Netherlands on 15 December 1954 in Aruba, Curaçao, the Netherlands, and Sint Maarten. When 15 December falls on a Sunday, the commemoration takes place on Monday 16 December. Kingdom Day is, unlike Koningsdag (English: King's Day), not an official national holiday, but government buildings are instructed to fly the flag of the Netherlands with an orange pennant.
The Charter for the Kingdom of the Netherlands was signed by Queen Juliana on 15 December 1954. The charter deals with the relation between the Netherlands and the overseas territories, the Netherlands Antilles, Netherlands New Guinea and Suriname. As of 2010, the charter governs the relationships between the Netherlands, Aruba (since 1986), Curaçao and Sint Maarten (since 2010).
Since 2005, the Koninkrijksconcert (English: Kingdom Concert) is annually held on 15 December, to celebrate the relationship between Netherlands, the Netherlands Antilles, and Aruba. At the concerts, that were held in respectively Dordrecht, Amersfoort, Nijmegen, and Curaçao, musical artists from all over the kingdom have performed.
In 2008, Naturalisatiedag (English: Naturalisation Day) in the Kingdom of the Netherlands was moved from 24 August, the day on which the Constitution of the Netherlands was signed, to 15 December, which has a symbolic meaning for all constituent countries of the kingdom. On Naturalisation Day, newly naturalized citizens officially receive their Dutch citizenship.
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- "When may I fly the flag and when not?". Dutch Royal House. Retrieved 2011-12-15.
- (Dutch) Koningin bij eerste Koninkrijksconcert in Dordrecht (2005-11-22). Ministry of the Interior and Kingdom Relations. Retrieved on 2009-07-10.
- (Dutch) Prof. mr. Pieter van Vollenhoven bezoekt Koninkrijksconcert (2007-12-05). Ministry of the Interior and Kingdom Relations. Retrieved on 2009-07-10.
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- (Dutch) Koninkrijksdag wordt naturalisatiedag. Radio Netherlands Worldwide. Retrieved on 2009-07-10.