Posted: 15 Nov. 2021 7 min. read



If there is the suspicion that an employee is behaving in breach of trust or contract with the employer (e.g. faking sick leave), and the employer wants to prove this, she or he will think about using a private investigator at this point at the latest.

In its decision of 25 March 2021, 8 ObA 8/21s, the Austrian Supreme Court clarified the question of whether an employer is entitled to compensation for the private investigators' costs from an employee who has faked sick leave.


The defendant employee had recently been on regular sick leave. The employer suspected – although the employee submitted certificates of incapacity to work – a "faked" incapacity to work and engaged a private investigation agency. They started their investigations and found that the employee who was reported unfit to work extensively enjoyed his free time. He was picked up from home around noon, then went to a coffee shop, which he left with friends around 3:30 p.m. and did not return home until 1:48 a.m. the following day. The detective agency informed the employer promptly, who instructed them to continue observing the employee. On the following days, the private investigation observed a similarly extensive free-time life of the employee who was allegedly sick. Based on the available results of the observation, the employer decided to end it. Immediately after, he issued the termination with immediate effect to the employee. In addition, he claimed full compensation from the employee for the costs of the private investigator.

Decision of the Austrian Supreme Court

The reimbursement of the costs of the private investigator by an employee requires that there is an "adequate typical causal connection" between the costs of the investigation incurred by the employer and the actual, i.e. concrete evidence of a breach of the contract. The employer may therefore not spend costs randomly or based on vague assumptions and hope that they will be reimbursed by the employee later.

Furthermore, it is assumed that the investigations are objectively necessary and that the use of private investigators was necessary to obtain the relevant information or to uncover the breach of contract. The employee does not have to reimburse the employer for observation costs that are obviously unnecessary, have no prospect of success from the beginning or are clearly inappropriate. Costs are in any case unnecessary if circumstances could have been easily proven otherwise, or costs in those cases in which the suspicion was not confirmed in hindsight.

In addition, the Austrian Supreme Court was confronted with the following three questions:

How long may an objectively justified observation last?

The principle of proportionality mentioned as a condition requires that compensable investigation costs are not only necessary in principle, but also to the respective extent. In the case at hand, the investigators established already on the first day that the employee was not at home due to sickness but was engaged in free-time amusements. Therefore, the employee argued that all subsequent investigations were no longer necessary and that these investigation costs could therefore not be charged to him.

In this regard, the Court ruled that the investigative activities on the two subsequent days were necessary. This is because the employee could still effectively - judicially - defend himself against a one-time violation. It would also be possible that the results of the first observation were due to a mistake in observation or a coincidence. Only when the employer can present well-founded evidence (about the faked inability to work) over a longer period, the investigative activity is completed. Until then, costs incurred are necessary and thus compensable. Furthermore, the Court stated that a three-day surveillance period is not to be considered exorbitantly long. This is even more the case as the employer is financially burdened by its obligation to continue to pay remuneration and therefore a correspondingly in-depth investigation is permissible.

Is there an upper limit for the reimbursement of costs?

In the case at hand, the employer demanded reimbursement of costs that exceeded the employee's monthly salary "by a multiple". The employer had paid around EUR 8,000 (net) to the private investigation agency for a total of three days of observation. The Court found that the employer was entitled to full reimbursement of the costs claimed. It highlighted that there is no general principle in employment law according to which compensation is basically limited to the monthly income or that the monthly income must be taken into account in the obligation to pay compensation.

Is there a duty to mitigate the damage?

Irrespective of the fact that there is initially no upper limit for the claim for compensation, the principle of the duty to minimize damage applies. Here, the claimant is obliged to keep the damage as low as possible. The damaging party must prove that the claimant did not (sufficiently) observe the duty to mitigate the damage and to what extent the damage could have been reduced. In the case at hand, it was determined that the amount charged to and paid by the employer did not exceed the usual price level of private investigation agencies. It cannot be assumed from the insignificant amount of the invoice that the employer could have successfully disputed its full payment obligation towards the private investigation agency. Thus, the burden of proof is on the employee as the damaging party to claim and prove that the employer specifically breached the duty to mitigate the damage, which the employee did not do.


If an employer has sufficient reasons to believe that an employee is faking sick leave, she or he can obtain clarification by engaging the services of a private investigator. If the employee's breach of duty is subsequently proven, the employer can claim compensation for the private investigator's costs. Whether the duration of the observation and the related costs were objectively necessary must be assessed in each individual case. In principle, there is no upper limit for the reimbursement of costs.

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Dr. Stefan Zischka

Dr. Stefan Zischka

Deloitte Legal | Jank Weiler Operenyi RA

Stefan Zischka ist Partner und leitet den Fachbereich Arbeitsrecht bei Jank Weiler Operenyi Rechtsanwälte (JWO), dem österreichischen Mitglied des globalen Anwaltsnetzwerkes Deloitte Legal. Seine Tätigkeitsschwerpunkte umfassen die Bereiche Arbeits- und Sozialrecht sowie Zivilprozessrecht (Litigation). Im Jahr 2017 schloss er sich JWO als Partner an. Vor JWO war Stefan Zischka als Rechtsanwalt in einer der größten Rechtsanwaltkanzleien Österreichs (CMS Reich-Rohrwig Hainz Rechtsanwälte) und als Legal Counsel in der Erste Bank tätig.

Mag. Christina Feistritzer

Mag. Christina Feistritzer

Rechtsanwaltsanwaerterin | Associate

Christina Feistritzer ist Rechtsanwaltsanwärterin bei Jank Weiler Operenyi RA | Deloitte Legal, der österreichischen Rechtsanwaltskanzlei im globalen Deloitte Legal Netzwerk. Ihre Tätigkeitsschwerpunkte liegen vor allem im Arbeits- und Sozialrecht sowie Fremdenrecht.