The primary rule is that you should be able to take holiday as free time in the context of employment. Sometimes, for a variety of reasons, you are not able to take out all your holiday days before your employment expires. In such cases, you are entitled to take out these days in pay instead.
Holiday days lost?
It appears that some universities claim that employee’s vacation has been lost because the opportunity to take out holiday as time off within the framework of the employment was there but was not taken. This is wrong.
Holidays may be taken as time off in the context of employment, saved for future use (for long term positions) or paid out as holiday pay but you do not lose them.
Contact your local Saco-S association or Academic Association if your university says you have lost your holiday days.
Unfortunately, also some universities have argued that when holiday has not been taken before the expiration of employment, the employee is obliged to retroactively apply for holiday in spite of the fact they worked on these dates. Time you have worked can never count as holiday. So never sign that you apply for/verify holidays taken when you have not taken/will not be taking them.
Contact your local Saco-S association or Academic Association if your university requires you to say that you had a holiday when you actually worked.