In order to calculate the notice period, when making an employee redundant, the employee’s behaviour will not be taken into account. On the other hand, if the notice period given is too short and during that period the behaviour of the employee justifies a dismissal for serious cause, the employee loses the right to claim the supplementary indemnity in lieu of notice, in other words account will be taken of the employee's behaviour.
In the Act of 3 July 1978, only two options are available for employers  wanting to make an employee redundant. Either an appropriate notice  period must be calculated according to the principles set out in, among  others, article 39 of the Act, or there must be serious cause, in line  with the principles set out in article 35 of the Act, and thus no notice  period will need to be calculated.
 
 Hence, in Belgian law there is no middle ground. Even if an employee’s  behaviour is in itself the sole reason for the redundancy, the employee  will not be penalised and thus the employee will remain entitled to a  severance indemnity. The behaviour mentioned above must, of course, not  merit a dismissal for serious cause, otherwise article 35 of the Act  will apply.
 
 This is in stark contrast to a recent ruling by the Court of Cassation  (Cass. 26 February 2007). This case pertains to the right to claim a  supplementary indemnity in lieu of notice if the original notice period  had been incorrectly calculated and was thus too short. The hitherto  valid case law was of the opinion that an indemnity in lieu of notice,  following the calculation of a notice period, is an acquired right and  therefore once this entitlement has arisen, the employee will not be  able to lose it.
 
 In the ruling cited above, an employee was entitled to a longer notice  period than given by his employer. During the, albeit insufficient,  notice period, the employee was dismissed due to serious cause. The  Court of Cassation upheld the prior judges’ reasoning that the behaviour  of the employee, during the notice period, did justify the loss of the  right to claim the supplementary indemnity. Conversely, this is not the  case for termination such as in the event of the death of the employee;  here, the heirs will be able to claim the supplementary indemnity.
 
 This recent ruling has overturned the case law that prevailed up to  then. This ruling has caused confusion within both the academic and  legal worlds and has left judges uncertain; some Labour Courts follow  this decision and others reject it. Those of the opinion that this  recent path chosen by the Court of Cassation will rapidly be abandoned  are, however, mistaken; in another more recent Court of Cassation ruling  in 2009 (Cass. 5 January 2009), the Court once again upheld the same  reasoning.
 
 Only time will tell if the behaviour of an employee will be able to  influence the length of the notice period and therefore the amount of  the indemnity in lieu of notice. If indeed such a path is chosen,  legislative reform would need to introduce a third option between that  of the dismissal in article 39 of the Act (and the articles mentioned  therein) and the termination due to serious cause provided in article 35  of the Act. It remains to be seen as to whether or not it would be  opportune to expand the legislation thus far applicable.