From the Handelsblatt archive: An employee always calls in sick on bridge days and Mondays? Companies have these legal options if they suspect fraud.
Berlin. The number of sick people in Germany has recently fallen slightly. According to data from the Techniker Krankenkasse, the total number of employee absences remains high. Accordingly, German employees reported sick for an average of around 18.6 days between January and November 2025. In the entire year of 2021, German employees were only absent for around 13 days due to illness.
But how many of them are really sick and how many are “blue” – i.e. just pretending to be sick? Nobody knows for sure, but there is evidence: according to a survey by the opinion research institute Yougov from last year, more than one in four people have given false information.
A recent study by the health insurance company Pronova BKK came to the conclusion that 60 percent of employees have called in sick even though they actually felt fit enough for work. Seven percent do this “often”. This happens “sometimes” or “rarely” for around half of those surveyed.
If an employee repeatedly reports sick even though he or she is actually able to work, the employer does not have to accept this. Two labor law specialists explain what legal options companies have to take action against such “sick parties”.
Reporting sick: Employees have these obligations
If an employee is ill, they must immediately inform their employer that they are unable to work and also how long the inability to work is expected to last. “The employee can use the telephone, email, SMS, WhatsApp or other messenger services,” says Markus Bohnau, specialist lawyer for labor law at the Kliemt law firm.
The employee currently only has to submit a certificate of incapacity for work (AU) if it lasts longer than three days. However, the federal government is planning to tighten this regulation so that a certificate of incapacity for work could be due from the first day. However, this has not yet been legally decided.
Nevertheless, the employer can now request an AU before the end of the three days, says Cologne lawyer Nathalie Oberthür. Since 2023, for those with statutory health insurance, this has been sent directly from the health insurance company to the employer as soon as the doctor has issued it.
If an employee is on sick leave, he must also behave in such a way that it does not affect his recovery, said the expert.
What exactly this means in practice varies from case to case. According to IG Metall, for example, you can go to the cinema or restaurant with a broken arm. However, anyone who is on sick leave with the flu or a gastrointestinal infection should stay at home.
There is no AU? This is how the employer can react
If an employee is sick, the company continues to pay their full salary for six weeks. However, if he cannot present an AU and cannot otherwise prove his inability to work, the employer has the right to refuse payment, according to legal expert Bohnau. Some companies also pay salaries for longer.
In addition, a company may also impose sanctions if an employee cannot prove their inability to work with a certificate - for example a warning or even termination.
Abnormalities in the sick note: When can an employer doubt an AU?
“The employer can question a certificate if there are reasonable doubts about its accuracy,” says legal expert Bohnau. These occur, among others, in the following cases:
The employee has announced his inability to work in advance - for example because his vacation request was rejected or there was a dispute with the boss.
The employee repeatedly takes sick leave shortly before or after vacation, weekends or public holidays.
The employer catches the employee engaging in behavior that is contrary to recovery - for example, because he goes to a party despite having the flu.
The employee terminates the contract and takes sick leave for the remainder of the contract term.
Suspicion of failure: What can companies do?
According to legal expert Nathalie Oberthür, if an employee fails, this can have far-reaching consequences and even lead to extraordinary dismissal. The catch for companies is that it must be proven that an employee has declared himself unfit for work even though he is not.
This is particularly difficult if there is a certificate. The doctor who issued the AU will usually not admit that he or she made a sloppy examination of the patient.
One option is to contact the medical service of the statutory health insurance companies, which can check the accuracy of the certificate and order an examination of the employee. According to Oberthür, if the employee does not appear for this examination, this can help to undermine the evidentiary value of the medical certificate.
“However, the health insurance company can also reject the report if the cause of the AU is clear from the medical documents,” says Oberthür. This means: If, after reading the diagnosis by the doctor who issued the certificate, the health insurance company comes to the conclusion that everything is correct, it does not have to prepare a report.
Medical service checks the accuracy of the AU
Another problem: It can take several days or even weeks until an employee is assessed by the health insurance company's medical service. It is then often difficult to check whether the employee was really sick.
Another option is to search for evidence yourself. In some cases, employers also consider hiring a detective agency to uncover a possible fake illness.
However, according to Bohnau, caution is advised here. On the one hand, a detective agency may only be called in if there are concrete facts that justify the suspicion of “hiding”.
On the other hand, surveillance would process personal data and thus interfere with the employee's personal rights. The detective must therefore adhere to data protection regulations. For example, he is not allowed to take photos on the employee's property or in the apartment with a telephoto lens.
Investigation: Suspicion must be based on concrete measures
The same applies if the employer wants to carry out their own investigations. According to Bohnau, he is bound to the rules of data protection like a detective. He also needs a well-founded initial suspicion, and the investigation must not be disproportionate in terms of type and scope.
If the employer violates his employee's personal rights through surveillance measures, this can be expensive for him. In 2023, the Düsseldorf Regional Labor Court awarded an employee compensation for pain and suffering after his employer had him monitored by a detective agency because of an allegedly faked inability to work.
According to the court, the employer should have taken less drastic measures beforehand. The use of a detective should only be considered if the suspicion of cheating is already based on concrete facts.
