That is not known. Today in the weekly royal blog of the NOS (the Dutch equivalent of the BBC): "The King's vacation is no holiday".
My translation of
the orginal text:
Like many Dutch, King Willem-Alexander and his family are on vacation. Whether the King spends his vacation in his villa at a Greek beach or elsewhere, remains secret for privacy reasons. The King made no secret that his vacation is not really a holiday.
During an interview with the press after the usual photo session on the eve of his vacation, the King stated that he remains head of state, also during the vacation: "You do not know what is coming. That is part of my fine work." In 2005 Queen Beatrix said, in an interview with Dorien Pessers (for her Silver Jubilee) that the never-ending availability was "one of the difficult aspects of the monarchy".
Here King Willem-Alexander seems to be less burdened. The King said that during this holiday he would study and read for his coming State Visit to China, in October and called it "a pleasure to do." Of course the remains continuously available for putting his signature to Acts and Royal Decrees. The King does that on a very tightly secured iPad.
After returning from vacation the King will again sign the original documents, but then by hand, all while keeping the original date of the first signing. Thanks to the digital revolution the times are beyond that special couriers had to travel to the holiday residence of the King.
In the Dutch constellation there is no remplaçant for the King, also not during illness, vacation or maternity. Often these replacements are arranged, far behind the comma. For example for members of the Cabinet. As Pthe Prime Minister is with vacation, his duties will be performed by the Vice Prime Minister. Is he also not there, then the most senior minister takes the honneurs. Ministers themselves are replaced by their state-secretaries.
The exception for the King when it comes to replacement is related to the strictly personal nature of his ohigh ffice. The King is neither lected nor appointed, but acquires his position by virtue of birth: the hereditary succession. In very exceptional cases, there may be an remplaçant for the King indeed.
Thus, the Constitution provides in Article 36 that King Willem-Alexander can lay down -temporarily- the royal authority "on his own initiative". But the Parliament, both Houses in a joint session, has to approve this by a special Bill. The royal authority comes then, as things are arranged, in the hands of Queen Máxima. She will then become Regentess of the Kingdom.
