Section 9 TzBfG establishes a legally enforceable right for part-time employees to extend their working hours by changing their contract if no more suitable competitors apply.
A claim to an extension of working hours according to Section 9 TzBfG requires that an “appropriate job” with longer working hours is available. If the employer culpably violates the part-time employee’s right to an extension of his working hours and he permanently occupies the workplace with another employee, there is a claim for damages due to the impossibility of performance. According to the ruling of the Ninth Senate of September 16, 2008 (9 AZR 781/07), the requirement for an “appropriate job” is generally only met if the position to be filled is comparable in terms of content to the job in which the part-time employee works carries out its contractually agreed activity.
Both activities must generally place the same demands on the personal and professional suitability of the employee. The part-time employee is only entitled to an extension of his working hours in exceptional cases if this is associated with a change to a job with a higher level of work. Such an exceptional case is to be affirmed if the employer’s personnel organization only allows part-time work at a lower hierarchical level than the one previously occupied. This creates a self-binding effect: the boundary between the two hierarchical levels becomes permeable to the part-time employee’s later wish to extend the contract. In this case, the workplace with the higher-value activity is also considered a “corresponding workplace” in the sense. § 9 TzBfG. The Ninth Senate has specified the concept of an urgent operational reason, which can be used against the part-time employee’s request for a change.
The employer’s desire, for cost reasons, to fill the vacant position with a candidate in his or her second year of employment who would be paid less under the collective agreement does not constitute a reason for filling the position with a part-time employee who is interested in extending their working hours opposes. It is therefore irrelevant whether a personnel cost budget is exceeded as a result of considering a request for an extension due to the automatic remuneration system in the collective agreement.