It appears that the chance of a prosecution for failing to attend a polling place on 26 May is nil, though this isn't the case for anybody called upon to serve as an election official. Recalcitrant election officials risk prosecution.
An easy way of getting out of the obligation to attend a polling station in person is to vote by proxy and get somebody else to cast your ballot, but this needs to be organised beforehand.
Attending a polling place and voting may be compulsory, but at the last general election in 2014 over one in ten voters didn’t bother or decided to protest by staying at home. Media outlet HLN learned that the names of recalcitrant voters are not handed to prosecutors. A VRT call to the justice department confirmed this.
Polling station presidents will compile a list of voters who fail to turn up. The lists are handed to justices of the peace, but a directive stipulates that only absent election officials are prosecuted. The lists are destroyed after six months.