If the non-European worker is a researcher, the type of authorisation varies based on whether or not they work in the frame of a hosting agreement and based on the duration of the employment in Belgium.
(art. 2,26 and 9,8 Royal Decree 09/06/1999)
The researcher works in Belgium in the frame of a hosting agreement (regardless the work duration)
You do not need to ask Brussels Economy and Employment for employment authorisation in order to work in Belgium. (automatic exemption by virtue of article 2.26 of the royal decree dated 9 June 1999)
The researcher works in Belgium for more than 90 days and four years at most (without a hosting agreement) (art. 9,8 royal decree 09/06/1999)Apply for a single permit
The researcher works in Belgium in the frame of a hosting agreement for maximum 90 days (without a hosting agreement) (art. 9,8 royal decree 09/06/1999)Apply for a work permit
(In case of successive jobs, the previous periods will be taken into account for the calculation of the 90 days. If the 90 days are exceeded, see the procedure for a single permit.)