As every body knows taxes are very high in Belgium lets make the example if you earn 6000 euro the goverment will take between 38 to 50% of you salary it depends your personal situation . So you get around 4300 after tax in the best case.If you live in belgium you have to pay other taxes for you house and many other things.
You don't come to belgium for the money they have a saying the more you work and earn the more the state will take from you .