In practice there are frequent cases of employer and employee not having the probation period stipulated as in the Labour Code. In such cases a question arises whether such provision about the probation period will be invalid, or in which of its parts.
Judicature is quite clear regarding such a question with the rule that if the duration of the probation period was stipulated unlawfully, it will always be a probation period lasting three months or less (with respect to the employment duration, details as follows). The same applies in cases when stipulation of the probation period duration is entirely missing in the contract.
The above mentioned will be valid only in cases when the probation period as such was stipulated correctly meaning in written and to the start date of employee’s employment at the latest. It is always necessary to differentiate invalidity of the probation period as such and partial invalidity of the provision about its duration.
Validity of the probation period stays unchanged even if it was stipulated in a separate document, it is not necessary to include the probation period directly into the text of the employment contract if the above-mentioned legal conditions were met.
A probation period in the length of 5 months was stipulated between employer and employee. Employer terminated employment with the employee in the probation period in the half of the fourth month of the probation period. Employer’s termination of the employment with the employee was invalid; even if the probation period was stipulated correctly, its duration exceeding three months is invalid. Employer then terminated the employment after termination of the probation period.
If the employer agreed on the probation period with the employee only verbally, such a legal action would be regarded as entirely invalid and probation period wouldn’t be applied between both sides.
Employment contract was stipulated between employer and employee where it was stated: "Probation period is stipulated from the start day of employment in the duration of .....", when the text wasn’t completed because of inattention of both contracting parties. Subsequently, in the course of a third month the employee delivered the employer termination in the probation period. Such legal action of the employee would be entirely lawful because the missing detail about the probation period duration only means that a three-month probation period was applied.
In practice cases of stipulating of the probation period in contradiction to Section 35(5), Labour Code may arise. In such cases a period equalling half of the fixed-term contract period is regarded as a stipulated probation period.
Mr. Novák and his employer stipulated fixed-term contract in the duration of four months with the probation period stipulated for the duration of three months. Such case means that the probation period was stipulated correctly, but its duration will only be two months (1/2 of the employment duration) and in this period it is possible to terminate the employment in the probation period. Termination of employment during the third month of the probation period would be invalid.
Miss Čechová was hired as executive producer. Probation period was stipulated for the duration of 6 months with the employment lasting for one year. During the fourth month of the employment duration Miss Čechová was lawfully dismissed from the working position and one week later her employment was terminated in the probation period. Miss Čechová´s probation period was stipulated correctly together with its duration because the law for managerial employees permits up to six-month probation period.
Doubts can be made about the time she was dismissed from her managerial position that and as an "ordinary" employee she can have only a three-month probation period. However, employment of Miss Čechová was terminated correctly because legal action is necessary to assess in the actual moment of its fulfilment. At the time of stipulating the employment contract and the probation period Miss Čechová was the managerial employee, probation period was then stipulated lawfully and additional loss of the managerial position doesn’t have any effect on the assessment of the probation period duration.
In case of a completely opposite situation meaning employee would be appointed into the position and employer would insist on prolonging of the probation period, there is no dispute about how to solve the situation. According to Section 35(4), Labour Code the probation period can’t be additionally prolonged, not even in case of appointing into the managerial position.
However, the contracting parties from the above-mentioned example can agree among themselves that the probation period will be shortened regarding the given circumstances. Law only explicitly forbids the prolonging of the probation period, not its shortening, together with keeping of the agreement by employer and employee. The prolonging ban is then applied for any kind of prolongation, thus for additional prolongation not exceeding the maximum lawful duration of the probation period.
In practice it is also very important to focus attention to the correct calculation of the probation period which is a period and not a time limit which has essential influence on its proceedings (see Section 333 Labour Code). When terminating employment during probation period I always recommend to deliver the documentation sufficiently in advance to get to the addressee the last day of the stipulated period at the latest; otherwise you risk invalidity of the employment termination.
 Supreme Court judgement as of 27 November 2001, file No. 21 Cdo 127/2001.
 Judgement of The Supreme Court of Czechoslovakia as of 31 March 1983, file No. 6 Cz 12/83.
 BĚLINA, Miroslav. § 35 [Zkušební doba]. In: BĚLINA, Miroslav, DRÁPAL, Ljubomír, BĚLINA, Tomáš, BOGNÁROVÁ, Věra, DOLEŽÍLEK, Jiří, NOVOTNÝ, Zdeněk, PICHRT, Jan, PUTNA, Mojmír, ROTHOVÁ, Eva, STÁDNÍK, Jaroslav, ŠTEFKO, Martin. Zákoník práce. 2nd edition. Praha: Nakladatelství C. H. Beck, 2015, p. 223.