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

As a rule, work rules are drawn up and amended by the employer, but when they are changed to the disadvantage of employees, the change has no effect without the employees' consent. The question is how that “consent” must be obtained, and in practice the mere fact that the employer has collected consent forms from its staff is often not enough.

Looking first at the statute, an employer who ordinarily employs 10 or more workers must prepare work rules and report them to the Minister of Employment and Labor, and the same applies when the rules are amended (Labor Standards Act Article 93 (근로기준법 제93조)). When amending the rules, the employer must hear the opinion of the labor union if one is organized by a majority of the workers, or otherwise the opinion of a majority of the workers; and where the amendment is disadvantageous to the workers, hearing their opinion is not enough and their consent must be obtained (Article 94(1) (제94조 제1항)). If an employer makes a disadvantageous change without going through the consent procedure, not only is the change void, but a violation of Article 94 is punishable by a criminal fine of up to KRW 5 million (Article 114, Subparagraph 1 (제114조 제1호)), and a breach of the duty to report or the duty to post the rules (Article 14 (제14조)) is subject to an administrative fine of up to KRW 5 million (Article 116(2), Subparagraph 2 (제116조 제2항 제2호)).

So how must consent be obtained? The Supreme Court holds that if there is a majority labor union, the consent of that union is required; if there is none, the employer must obtain the consent of a majority of the workers through a meeting-based process in which the workers, free from the employer's involvement or interference, exchange views and gather their votes for and against, either across the whole workplace or by organizational unit or department. As an example, in a case where a company that extended the retirement age while introducing a wage peak system posted the amendment and a consent form on its intranet and collected individual consents over 7 days, with 3,857 of 4,906 workers in total (about 78%) consenting, the Supreme Court held that consent by collective decision-making could not be found, pointing out that the labor union which had engaged in collective bargaining was not a union organized by a majority of the workers, that the briefing sessions had not been held for all workers, and that the explanation of the disadvantages of the wage peak system had been insufficient. In other words, even if there are consent forms exceeding a majority in form, the change is not recognized as consented to unless it is accompanied by collective decision-making in which opinions are exchanged and votes for and against are pooled (Supreme Court Decision 2025Da215010, June 25, 2026 (대법원 2026. 6. 25. 선고 2025다215010 판결)).

Then, is there no way to amend work rules when consent cannot be obtained? The Supreme Court formerly held that if the amendment was reasonable by social norms, it could be effective even without consent, but it changed this position in 2023. Where the employer has failed to obtain consent through the workers' collective decision-making method, the validity of the amendment cannot be recognized merely on the ground that it is reasonable by social norms, unless there are special circumstances indicating that the labor union or the workers abused their right of collective consent. The Court held that an abuse of the right of collective consent refers to a case where the need for the amendment is objectively evident due to changes in laws or the social environment and the labor union or the workers oppose it without reasonable grounds despite the employer's sincere efforts to persuade them, and that this must be judged strictly (Supreme Court en banc Decision 2017Da35588, 2017Da35595, May 11, 2023 (대법원 2023. 5. 11. 선고 2017다35588, 2017다35595 전원합의체 판결)). In the end, even if an amendment to work rules is reasonable, skipping the consent procedure is, as a rule, no longer an option.

Meanwhile, even where a change is void for lack of consent, its effect is not the same for every worker. The Supreme Court held that an amendment to work rules made without consent does not take effect against existing workers whose vested interests are infringed, but that the amended work rules naturally apply to workers who, after the change, entered into an employment relationship accepting the working conditions under the amended rules (Supreme Court en banc Decision 91Da45165, December 22, 1992 (대법원 1992. 12. 22. 선고 91다45165 전원합의체 판결)). Accordingly, if majority consent to the change was not obtained, the former rules apply to existing workers while the amended rules apply to those hired after the change, which can result in two different sets of working conditions within a single workplace.

In summary, when amending work rules to the disadvantage of employees, first check whether there is a majority labor union; if there is none, set up a procedure in which, after department-level briefings and discussion, votes for and against are pooled without the employer's involvement, and keep a written record of that process. It is important to bear in mind that merely having collected consent forms is not enough.