The Aliens' Department now says that he hasn't lived here long enough in order to qualify.
Three months ago Bernard Arnault announced that he was applying for Belgian nationality in Ukkel, the affluent Brussels suburb where he had bought a house.
M Arnault is the CEO of the luxury goods manufacturer LVMH or Louis Vuitton Moët Hennessy. He decided to move to Belgium to sidestep new taxes on the extremely rich imposed by France's socialist President François Hollande, but the multimillionaire apparently failed to read the conditions properly.
The Aliens' Department says that residence of three years is required before Belgian nationality can be conferred.
M Arnault's hopes have not entirely been dashed. The Belgian parliamentary commission that considers naturalisations takes account of three different recommendations and the one from the Aliens' Department is only one of these. The Public Prosecutor's Office and the State Intelligence Service also have to have their say.
At the end of the day it is the parliamentary commission that takes the final decision and it can ignore all recommendations. A decision could take many months in coming though.