On 1 January 2014, the Belgian legislation with regards to the dismissal of employees was thoroughly reformed, as the periods of notice, which were different for white collar and blue collar workers, were equalised for both categories. However, transitional provisions stipulate that the period of notice for an employment contract concluded before 1 January 2014 must be determined in two steps, where for the first step the seniority until 31 December 2013 has to be taken into account and for the second step the seniority since 1 January 2014. Each step has its own calculation rules. In the absence of legislative rules, the question is whether the individual contractual clauses relating to the period of notice to be respected by the employer validly concluded before the reform, still apply. The discussion led to multiple opinions in the doctrine. In case law, there are three tendencies. The Labour Court of Antwerp judged on 16 June 2015, that, as regards the calculation of the first step of the period of notice, the contractual clause must be taken into account, even though the clause may be less favorable for the employee than the new calculation rules. With this judgment, the Labour Court of Antwerp supports the opinion that such clause still applies, but only for the first step of the calculation. More recently, two other courts judged differently. The Labour Court of Brussels ruled on 25 May 2016, that contractual clauses preceding 1 January 2014 are no longer applicable, so that only the new rules regarding the two steps of the calculation of the period of notice must be applied. To the contrary, the Labour Court of Mechelen ruled on 11 October 2016, that such clauses apply for the two steps of the calculation of the period of notice, so that the new legal rules are totally set aside. Uncertainty remains on this issue.