Korean filing deadlines: finding the ones that apply to you

1. Where a deadline comes from

A filing deadline in Korea is set by statute, not by custom. Article 49(1) of the Value-Added Tax Act says the final return is due within 25 days after the taxable period ends, and Article 5(1) of the same Act says when that period ends. You need both articles before the dates 25 January and 25 July appear.

That is why the same article produces different answers for different businesses. Article 5(1) gives a simplified taxpayer one taxable period covering the whole calendar year, while a general taxpayer gets two six-month periods. The number 25 is the same; how often it comes around is not.

Corporate tax is not tied to the calendar at all. Article 60(1) of the Corporate Tax Act sets the deadline at three months from the last day of the month in which the fiscal year ends. With a December year end that is 31 March; with a June year end it is 30 September. That is why this page asks for your fiscal year end.

2. What each type owes

A general-rate sole proprietor files VAT twice a year: on 25 January for the second half of last year and on 25 July for the first half of this year. On 25 April and 25 October there is no return, only a payment against an assessment, because Article 48(3) of the VAT Act has the tax office collect half of the previous period's tax. The proviso to that paragraph says no assessment is issued when the amount is under 500,000 won.

A simplified taxpayer files once, on 25 January, because the taxable period is the whole year. On 25 July there is a preliminary assessment to pay, and Article 66(3) adds a filing duty for that date if a tax invoice was issued during the period.

A VAT-exempt business files no VAT return but must report its business status by 10 February under Article 78(1) of the Income Tax Act. Global income tax is due on 31 May for any individual, whatever the VAT status.

Corporations actually file the preliminary returns. What is a payment date for a sole proprietor on 25 April and 25 October is a filing date for a corporation.

3. The rules inside this app

The page asks five questions: sole proprietor or corporation, VAT general or simplified or exempt, whether you withhold, whether you hold an approval for half-yearly withholding payment, and for a corporation the fiscal year end month. Those five values select from twenty-one deadline rows.

Half-yearly withholding is offered only as an approval you already hold. Article 186(1) of the Enforcement Decree of the Income Tax Act limits it to a withholding agent with twenty or fewer employees on average in the previous year who has been approved by the head of the tax office or designated by the Commissioner. Paragraph 3 of the same article says the application runs from the first to the last day of the month before the half-year begins. This page does not judge whether you qualify; it calculates what you picked.

Dates are not written into the screen. Each deadline row carries only its recurrence, and one place turns that into dates. A fixed day of the month, the last day of the month, a fixed day of the year, and an offset from the fiscal year end are each counted differently. The last day of February is 29 in a leap year.

When a deadline falls on a Saturday, a Sunday, a public holiday, a substitute holiday or Labour Day, it moves to the next day. Article 5(1) of the Framework Act on National Taxes says so, and Article 24(1) of the Framework Act on Local Taxes repeats the wording. Some years a long holiday sits against a weekend and the shift runs more than two days, so the shift repeats until a working day is reached. The screen shows the statutory date and the actual date side by side and names the reason.

The holiday table is taken as it stands from our sibling public holiday app. It covers 2024 through 2030, and years outside it are not calculated. Labour Day is not a government office holiday and so is absent from that table, but the statute names it, so this app counts it separately.

The calendar file is built inside the page. It holds all-day events, and the one-day and one-week reminders become alarms inside the file. Our server sends no reminders, so it has no reason to hold an address. It learns only that the page opened, that a list appeared, that a file was downloaded and that a link was copied.

Your choices live in the address bar. Nothing is stored, so a bookmark brings back the same list and deleting it leaves nothing behind.

4. Where people get it wrong

A preliminary return and a preliminary assessment are different things. What a sole proprietor receives on 25 April is a bill, not a filing duty. Article 48(4) of the VAT Act does allow filing instead of paying the assessment when business has fallen off for reasons the Presidential Decree lists.

Local income tax is counted separately from national tax. Ten percent of the withheld income tax goes to the local government, due on the same 10th of the month. A global income return in May carries a local income return on the same deadline. Because the recipient differs, it is easy to assume the job ended at the national filing portal.

Local corporate income tax comes a month after corporate income tax, because Article 103-23(1) of the Local Tax Act says four months where Article 60(1) of the Corporate Tax Act says three. With a December year end that is 30 April against 31 March.

Payment statements split across two dates. Article 164(1) of the Income Tax Act sets the last day of February as the rule and 10 March for wages, severance, business income, clergy income and service charges. For daily workers the statement is due at the end of the month following payment, so it comes around every month.

5. A little deeper

The simplified payment statement is a monthly deadline. Article 164-3(1) of the Income Tax Act sets it at the last day of the month following payment, covering wages to non-daily employees, business income subject to withholding, and the other income described in Article 21(1)19 of the same Act.

The wage total report is insurance, not tax. Article 16-10(1) of the Act on the Collection of Insurance Premiums for Employment Insurance and Industrial Accident Compensation Insurance requires last year's total wages to be reported to the Service by 15 March every year. It goes to the Workers' Compensation and Welfare Service rather than the tax office, so this page names the recipient separately.

A taxpayer subject to the honest-filing confirmation has a different global income deadline. Article 70-2(2) sets it from 1 May to 30 June. Who falls into that group depends on a revenue threshold in the Presidential Decree, which we could not read, so this page does not offer that option.

If a corporation's fiscal year does not end in December, the VAT deadlines stay put and only the corporate ones move, because the VAT taxable period is fixed to the calendar rather than the fiscal year. Changing the fiscal month on this page shows that difference directly.

6. Getting stuck

If no VAT assessment arrived, the amount may be under 500,000 won. Article 48(3)1 of the VAT Act says nothing is collected in that case. This page does not know your amount, so it shows the date regardless.

An empty list means no deadline in this table applies to the combination you picked. A VAT-exempt corporation is one such case, because the business status report sits in the Income Tax Act and reaches individuals only.

If the calendar file looks a day long when you expected a single day, that is the all-day end date. In the standard format the end of an all-day event is exclusive, so the file holds the following day and the calendar draws one day.

Years after 2030 are not listed, because the holiday table stops there and counting an unknown year as holiday-free would shift a deadline without saying so.