Important South Korean Tax Reporting Requirements Coming Due (for the fiscal year ended December 31, 2025)

l 2025 annual corporate income tax and local income tax return filing deadlines

Under the Corporate Income Tax Law (“CITL”), a company having a fiscal year ended December 31, 2025 should file the 2025 annual corporate income tax return by March 31, 2026 together with necessary tax payments thereof.

In this connection, we summarized the due dates of tax return filing and necessary tax payment related to corporate income tax and local income tax as follows.

In principle, annual/interim corporate income tax and local (provincial) income tax returns are due filing together with tax payment as given below:

If the annual/interim corporate income taxes payable are over KRW 10 million (KRW 1 million for local income taxes payable), companies are allowed to make tax payments in 2 installments as below:

(*) The amount of installments shall be determined as follows:

l Transfer pricing (TP) and BEPS requirements

Under the International Tax Coordination Law (“ITCL”), which governs the taxation of international transactions between taxpayers and overseas specially related parties (OSRPs), a company is obliged to submit the following documents for the transactions with its OSRPs during the fiscal year to the relevant tax office within 6 months from the fiscal year-end:

a. Report on the method of arm’s length price determination

b. Schedules of international transactions with OSRPs

c. Summarized Profit and Loss Statement of OSRPs

In relation to the BEPS requirements, multi-national enterprises (MNEs) which meet the following conditions are also required to submit the Combined Report of International Transactions (CRIT) which is comprised of three elements (Local file, Master file, and CbC report).

l 2025 individual income tax return filing deadline (due by June 1, 2026)

Residents, regardless of their nationality, are subject to Korean income tax based on worldwide income including global income (employment income, business profits, dividend, pension, interest, rental, and other miscellaneous income), severance pay, and capital gains.

However, under the revised Individual Income Tax Law (“IITL”), in the case where the period that a foreigner, who is a tax resident of Korea, has his address or abode in Korea does not exceed 5 years in aggregate during the past 10 years from the end of the applicable tax year, his/her foreign source income earned from January 1, 2009 shall be taxed in Korea only if such income is paid in Korea or such income is remitted into Korea.

Taxpayers making monthly tax payments and having only one source of worldwide income (i.e., either Class A or Class B) are generally not required to file a global income tax return since the employer (for Class A income earners) or the Class B taxpayers' association (for Class B income earners) finalizes the individual's tax liability at the end of the year for and on behalf of the employee concerned. Taxpayers having more than one source of income, however, are required to file a global income tax return for the year and pay taxes due on such income on or before May 31 of the following year, or prior to permanently leaving Korea.

The filing of 2025 annual individual income tax return is coming due on June 1, 2026 together with necessary tax payments.

For more details, our tax advisors will be able to provide a thorough consultation upon request.

l Global minimum tax (GloBE Rules) filing requirements

The Global minimum tax is a new international tax framework designed to ensure that multinational enterprise (MNE) groups pay a minimum effective tax rate of 15% in each jurisdiction where they operate. If the effective tax rate in a specific country falls below 15%, an additional "Top-up Tax" is levied to cover the difference.

This rule applies to MNE groups with consolidated annual revenues of EUR 750 million (approx. KRW 1 trillion) or more in at least two of the four preceding fiscal years.

Korea has implemented the GloBE rules starting from the 2024 fiscal year.

· Initial Filing (FY2024): By June 30, 2026 (The later of 18 months after fiscal year-end).

· Regular Filing (From FY2025): Within 15 months after the end of the fiscal year.

Required documents for submission