In Germany, you have a legal right to holiday time.
In principle, this is calculated as four working weeks over the whole year
This means: For a 6-day working week it is 24 days, for a 5-day working week it is 20 days, etc.
Holidays do not count towards Sundays and public holidays. Public holidays are different in every federal state!
It is customary to take a holiday once a year. This should last at least two consecutive weeks. This has been established by case law. The employer can only refuse longer leave in very serious cases.
The leave days must normally be taken within one calendar year, otherwise they may be forfeited. There are exceptions, for example in the case of illness or maternity, or (collectively agreed) contractual regulations.
During the leave, the usual salary continues to be paid. There is no entitlement to continued payment of reimbursements, such as travel expenses.
Special provisions in collective agreements
In collective agreements, employees are usually granted more leave days than required by law. Persons engaged in heavy or hazardous work are often entitled to additional days off. Some collective agreements also have provisions for special leave, for example for marriage or the death of a family member, sometimes for moving house. Special leave is not regulated by law in Germany.
The right to the full number of days of leave can only be claimed after you have worked for at least six months (waiting period). even during the probationary or waiting period, employees acquire a right to pro rata leave. For each full month, you get 1/12 of the number of annual leave days.
In most cases, employment contracts or collective agreements state that leave days not taken in a year must be taken by a fixed date. Exceptions apply, for example, in the case of prolonged illness. For example, if you have been sick for a whole year, your leave does not expire. You must take these days of leave in the year in which you can return to work.
If you cannot take your leave for certain reasons, e.g. because you have changed jobs, these days can be paid out.
There is a difference between holiday pay (vakantiegeld) and leave remuneration. Leave remuneration is a salary continuation during holidays and is required by law. Holiday pay is a special payment and is not regulated by law.
There is a regulation in most contracts and collective agreements and sometimes also in employment contracts.
If your employment contract explicitly states that holiday pay is paid voluntarily and without obligation, you are not entitled to this holiday pay. Then it is possible that you get something one year and not the next.