Tax registration with the authorities :
Belgium
Tax registration with the authorities
If planning on staying/working/buying a house or car, you must obtain a Social Security Number. This number identifies you to the Belgian taxman and is required when dealing with the tax office or health insurance companies. If you are employed, your employer will arrange this for you, however if you are self employed, you must arrange this yourself by contacting the National Office of Social Security.
Diplomatie - Social Security
Registration with the taxman is also essential, your employer should will do this for you. If you are self employed please talk to an accountant to ensure everything you do is legal. Contact details for your local tax office can be found via your local town hall.