Can my employer make me work overtime if my colleagues are sick and unable to work?

Overtime must always be agreed upon beforehand: in the employment contract (Arbeitsvertrag), in a company agreement (Betriebsvereinbarung) or in a collective agreement (Tarifvertrag). If there is no agreement, the employer may not order overtime without your consent. In exceptional situations, the employer may require you to work overtime. This applies, for example, if the employer can use overtime to ward off damages that threaten the company and that cannot be avoided otherwise.