Hello, this is attorney Choi Jong-ha of Cheongchul Law Firm.

More and more people are taking on side work after hours to earn income beyond their salary, whether through delivery or designated-driver services, lectures and consulting in their own field, or especially by monetizing YouTube and social media content. HR managers, too, often ask us, “We found out that an employee has a side job; how should we handle it?” Many companies have a rule stating that “employees may not engage in outside work without the company's permission,” so can a company discipline an employee for the mere fact of having a side job? To state the conclusion first, a side job in itself falls within the scope of freedom of occupation, and a blanket prohibition in company rules has its limits.

That freedom, however, is not protected without limit. Some side jobs remain on the borderline, while others amount to a legitimate ground for dismissal.

1. In principle, holding a side job is part of an employee's private life, but it must not interfere with the main job.

The courts have maintained a fairly consistent starting point on side jobs and dual employment. In a case involving a transport company, the court held that “an employee engaging in another business is a matter within the scope of private life according to the employee's individual ability, and it is not permissible to comprehensively and entirely prohibit even dual employment that does not interfere with corporate order or the provision of labor” (Seoul High Court, Judgment of Apr. 26, 2024, 2023Nu47512).

This holds true even where company rules contain a non-compete clause. A clause stating that “an employee may not engage in another occupation without the company's approval” does not by itself uniformly prohibit all side jobs; in principle it is construed restrictively, as limited to side jobs that disrupt corporate order or the performance of the main job. In other words, a single line in the company rules cannot block all of an employee's side work; the rule takes effect only where the side job substantially affects the main job or infringes the company's legitimate interests.

In the transport-company case as well, the decisive reason the court ultimately upheld the dismissal was that the side job substantially disrupted the main job. After a taxi driver started a designated-driver side job without the company's approval, his monthly taxi-driving hours plummeted from 57 hours to 14 hours and then to about two hours, and his business revenue fell at the same time. Once these circumstances were confirmed by objective figures, the court found that the side job fell within the realm of “dual employment that disrupts the main job” restricted by the company rules, and recognized the legitimacy of the dismissal.

In another case, an employee of a pharmaceutical company held a side job in a different industry at night for about six months, which led to an accumulation of frequent tardiness and unexcused absences and to problems in performing the main job due to drowsiness during work hours. Once these circumstances were proven, the court decisively focused not on the outward form of the side job but on its substantial effect on the main job, and held the dismissal to be legitimate (Seoul Administrative Court, Judgment of Jun. 27, 2025, 2024GuHap72476).

2. A side job at a competitor can be a ground for dismissal

Separately from disruption of the main job, if a side job is carried out in an area that competes with the company, it constitutes a ground for dismissal in itself, regardless of whether company rules exist. This is because an employee owes a duty of good faith, as an ancillary obligation under the employment contract, not to infringe the employer's legitimate interests, and at the core of that duty lies the non-compete obligation.

In a case where a weekly news magazine reporter, during an internal disciplinary dispute, set up a company that published a competing outlet together with colleagues and personally acted as its representative director and publisher, the Supreme Court held that the act of publishing the competing outlet constituted a separate ground for dismissal amounting to a breach of the non-compete obligation, and that it reached a degree at which continuing the employment relationship was difficult under generally accepted social norms, so the dismissal was not an abuse or deviation of disciplinary discretion (Supreme Court, Judgment of Sep. 27, 2012, 2010Da99279). The moment a side job reaches into the territory of a competitor, even if the company rules do not expressly prohibit it, that side job can be seen as falling outside the realm of private life.

[1] First instance: Seoul Administrative Court 2021GuHap76484, plaintiff lost; the appellate court maintained the result, and it was finalized by the Supreme Court's dismissal of the appeal without review, 2024Du42932.

[2] First-instance judgment; whether an appeal was filed is unconfirmed.