Our European and Belgian regulators impose various obligations on employers.
For example, you may not discriminate during recruitment, even indirectly. Not based on gender or sexual orientation, but also not on the basis of any of the 28 or so other criteria.
You must comply with European rules regarding the processing of personal data and are therefore not allowed to ask the applicant anything.
In addition to a fixed salary, you, as an employer, will often offer other benefits. When designing your salary package, it's best to consider the benefits stipulated by sectoral collective bargaining agreements. Most of these are subject to specific rules. Consider the use of a company car or bicycle, meal vouchers, pension, disability, or hospitalization insurance.