It really depends if you are going to be resident in Belgium, or somewhere else (France, UK...).

First of all you have to know that umbrella company is an English concept and it does not exist as such in Belgium. You might find companies that either provide the service for a short period of time (i.e. the consultant has got a 6 months contract in Belgium for example) or with offices in Belgium.

Below are a few addresses that you might contact to see if it can work for you:
- http://www.cpmpeople.com/
- http://globosolution.com/
- MSL Payroll for residents in Belgium

And as usual, pleas keep us in the loop to tell us what happened

 

What is legal? €375/day? Some contractors in IT get €800 or more, so there is no problem with that.
Tax in Belgium is very high (~50% - they tax the people who work, and leave in peace the people who live on Capital gain... that is strange for many people but so far no revolution yet ). You will get more information in our guide about expatriation in Belgium.
Just be careful with some amazing proposals to save plenty of tax... I heard that 2 years ago they caught about 800 IT contractors who were using umbrella company to put abroad most of their salary with no tax.

Best advice is to get in touch with some umbrella firms, they will probably be able to give you more information.

 

As I said, it depends under which circumstance. Take the example of a UK contractor going to work in Brussels for 6 months. I assume he can still stay under his UK umbrella company and be taxed in England.
In your case I have big doubts it is possible, but you will need to get proper advice.