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From traditional second jobs such as food delivery and designated driving to YouTube, social media and online stores, more and more employees now run a side job after hours. With that comes the question: can the employer stop it? The short answer is that in principle it cannot — but there are clear exceptions, and falling into one of them can lead to disciplinary action.

[Table of Contents]

1. The principle — hours after work belong to the employee

2. Does a "no moonlighting" clause in company rules ban every side job?

3. Three situations that can justify discipline

4. What an employer must actually establish to discipline

5. Public officials and public institutions follow stricter rules

1. The principle — hours after work belong to the employee

An employment contract is an agreement to provide labour during defined working hours in exchange for wages. Time outside those hours falls, in principle, within the employee's private life.

An employer therefore cannot impose a blanket ban on side jobs simply because it dislikes them. Earning income through delivery work, designated driving or content creation is a matter for the employee to choose.

2. Does a "no moonlighting" clause in company rules ban every side job?

The most common response is: "But our rules of employment say no secondary work without company approval."

Such a clause does not mean that every side job is automatically prohibited. Korean practice and case law read moonlighting clauses narrowly, as directed at secondary work that disrupts business order or impairs performance of the primary job. A clause purporting to impose a complete and general ban on an employee's private and occupational activity is unlikely to be upheld in full.

In other words, even where the wording reads as an absolute prohibition, its effective scope is confined to side work that affects the primary job.

3. Three situations that can justify discipline

Read the other way round, the following types of side work can constitute grounds for discipline.

• Impairing performance of the primary job — repeatedly falling asleep during working hours because of night-time side work, or a visible drop in focus and output.

• Disrupting business order — using company equipment, materials or working hours for the side job, or trading on the company's name and one's job title in a way that damages its reputation.

• Working in a business that competes with the employer — providing labour to a competitor or running a directly competing business, which also engages the employee's duties of non-competition and confidentiality.

The third category can persist beyond the end of employment, where post-employment non-compete and non-solicitation covenants come into play.

4. What an employer must actually establish to discipline

Article 23(1) of the Labor Standards Act (근로기준법 제23조 제1항) prohibits an employer from dismissing, suspending or reducing the wages of an employee without justifiable cause. Discipline based on a side job is subject to that same standard.

A formal breach of internal rules is therefore not enough. The employer must identify what concrete harm the side job caused to the primary job or to business order. In practice, that means assembling the following.

1. The specific impairment — attendance records, work errors or incidents, and objective evidence of reduced performance

2. Causation — the change before and after the side job began

3. Whether a competitive relationship exists — whether the sector and customers of the side job genuinely overlap with the employer's business

4. Proportionality of the sanction — consistency with how comparable cases involving other employees were treated

The same applies from the employee's side. Documenting that the side job is entirely separate from working hours and company resources and is not in a competing sector provides the starting point for a defence in disciplinary proceedings.

5. Public officials and public institutions follow stricter rules

The discussion above assumes an employee in the private sector. Public officials are, under Article 64 of the State Public Officials Act (국가공무원법 제64조), generally barred from for-profit work and concurrent positions and must obtain permission from the head of their agency. Public institutions and certain financial companies frequently impose stricter internal standards as well.

Side income also brings tax and social insurance reporting obligations — and that is usually how the employer finds out. It is worth checking before starting.

In short, a side job after work is free in principle. It becomes a legal problem the moment it affects the primary job or causes loss to the employer.

Consult Cheongchul Law Firm on moonlighting clauses and discipline

With moonlighting clauses, how the rule is applied matters more than how it is worded. Confirming in advance how far rules of employment can validly reach, and which side jobs fall within a safe range, removes much of the scope for dispute.

Cheongchul Law Firm handles employment matters directly — revising rules of employment and HR policies, advising on disciplinary procedure, remedy applications and litigation over unfair discipline and dismissal, and non-compete disputes. If you are considering discipline over a side job, or have received a disciplinary notice, please reach out through our consultation request page.

This post is general information for reference only and does not constitute legal advice on any specific matter. The validity of a moonlighting clause and the justification for discipline depend on the content of the rules of employment, the nature of the side job and the actual impact on work, so please consult a qualified attorney.