Side hustle taxes for Korean office workers compared, day jobs, one-off talks and freelance income

2026-10-14

Scroll through side hustle videos on the subway home and the list runs past delivery, online stores, teaching and e-books. Few of them say what kind of income that money becomes under the tax law.

For office workers in Korea, that split matters as much as the amount. The same money can mean different tax taken up front, a different answer on the May filing, and a different health insurance rule, depending on the type of income.

This post covers Korean rules for people with a salaried job in Korea. It does not pick or recommend any side hustle. We only copied the standards written by the National Tax Service (NTS), the National Health Insurance Service and the statute text, and set them side by side.

1.The three boxes side hustle money falls into

• Daily wage income: pay for work under three months, paid by the day or hour worked
• Other income: a one-off fee for a service such as a talk or a piece of writing
• Business income: money from doing the same work continuously and repeatedly (freelancers who have 3.3% withheld, online selling and so on)

The NTS treats someone whose employment contract runs three months or more as a regular worker, not a daily worker, even if they quit earlier.

Even for a weekend job, the contract period comes first.

2.The three compared: tax withheld, the May filing, health insurance

Day jobs: withholding ends it

The NTS formula for daily workers takes the day's pay minus 150,000 won, applies 6%, then cuts that tax by 55% (NTS daily wage income).

At 200,000 won a day, 50,000 won times 6% is 3,000 won, and taking off 55% leaves 1,350 won. That is 2.7% of the part above 150,000 won, with local income tax added separately.

Daily wage income is settled by the tax withheld at payment, so it goes into neither year-end settlement nor the May filing.

One-off talks and writing: choose at the 3 million won line

For a fee from a one-off service, 60% of the amount received is deducted as necessary expenses, or the actual expenses if they are larger. Then 20% of the remaining other income amount is withheld, plus 10% of that tax as local income tax (NTS other income withholding).

A talk paid 500,000 won leaves an income amount of 200,000 won, so 40,000 won plus 4,000 won in local tax comes off. That is 8.8% of the fee.

Other income amount: the money received minus necessary expenses. The lines below use it.

The NTS says that if withheld other income amounts total 3 million won or less in a year, the earner can choose to add them to other income in the filing or let the withheld tax end it (comprehensive and separate taxation).

With 60% expenses, that is up to 7.5 million won received.

Income Tax Act article 84 does not tax other income of 50,000 won or less per payment.

With the same 60% expenses, that is up to 125,000 won per payment.

The same talk can make the May filing a choice or a duty, depending on how many are given in a year.

Ongoing freelance work and selling: recalculated in May

Personal service business income has 3.3% withheld up front, and is added to salary income in the comprehensive income tax filing the following May. Without a filing on time, any overpaid tax is not refunded (NTS filing guide). A worked 3.3% case is in the computer side jobs post.

From the same 5 million won, the amount taken first ranges from 33,750 won (local tax separate) to 440,000 won.

Taking more up front is not always worse.

Other income can end there, while business income may owe more or get money back in May.

Health insurance and a second employer

The health insurance service charges extra to employee members whose income outside salary is over 20 million won a year. It counts the full income amount for business and other income, and half for salary and pension income (NHIS guide).

Working for another company on a contract of three months or more means salary income from two places. Under Income Tax Act article 73, such a person is not excused from the May filing unless the year-end settlement leaves no tax to pay.

3.Company rules to check before tax

Labor Standards Act article 93 requires a company that regularly employs 10 or more people to draw up and report work rules. Side jobs for company employees follow those work rules and the employment contract, so look up both documents before choosing.

!Public officials differ: State Public Officials Act art. 64 bans profit work and requires permission for other posts.

The Ministry of Personnel Management treats work done on a regular cycle, such as daily or weekly, or work there is intent to keep doing, as continuous. Unless the work is clearly not continuous, it says to apply for permission (MPM side-job permission).

Before picking from a side hustle list, write down which of the three boxes it falls into and whether company rules allow it. Choosing by time is covered in the side hustle ideas post.

4.Common questions

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