As a rule, your employer determines when you have a break as part of their right to issue instructions. These breaks are usually fixed in advance. It is also possible that the employer merely specifies a time frame in which the break is to be taken (e.g. 30-minute break between 12 noon and 2 p.m.). Similarly, in appropriate circumstances, the employer may, in accordance with Section 4 of the Working Hours Act (ArbZG), use its right to issue instructions to specify longer breaks than the legally prescribed 30 or 45 minutes if circumstances require this.