When we look to his former "colleague" Princess Beatrix: she lives on her privately owned estate, in a beautifully restored countryside mansion. However the Government spends nearly 4 million Euro to refurbish Noordeinde 66 (a city mansion next to, and connected with, Noordeinde Palace in The Hague) as a pied-à-terre
for the Princess. Not for living, just for when she is in The Hague and receives guests, then she can do that in surroundings which befit her position as former Sovereign. Also her particulier secretariate will have offices in that mansion.
I think I can follow the way the Dutch Government thinks. King Juan Carlos is the former Sovereign. He needs a place and an office which fits to his stature as former Sovereign.
Pic: the monumental Louis XV-style mansion for Princess Beatrix is in scaffoldings: http://haagspraak.files.wordpress.co...1203_31471.jpg
She can retreat there when she is in The Hague, can receive her guests in a splendid interior, has her own staff, offices, etc. Despite having abdicated as Queen, she of course holds a high status and apparently it was thought "fitting" to have an own office rather than making use of Noordeinde Palace, Huis ten Bosch Palace, the Royal Palace Amsterdam or other royal residences. It has a considerable prize tag but so far the upset seems not to be too big.