Executive summary
Two administrative questions matter more than they first appear for a foreign corporation operating in Korea: what fiscal year (business year) governs its Korean tax filings, and which tax office (tax domicile) has jurisdiction over it. Both are procedural — but both come with deadlines that, if missed, don't just cause paperwork friction; they change the fiscal periods Korea will assume for the company by default, and can affect which office ends up reviewing its filings.
This guide covers how a foreign corporation sets and changes its business year, what happens when it doesn't report one at all, and how Korean tax domicile is determined for foreign corporations with a Korean place of business, real estate income, or multiple locations.
Who should read this
- Foreign corporations newly establishing a Korean branch or place of business
- In-house tax managers coordinating fiscal year alignment with headquarters
- Companies with Korean real estate income but no Korean place of business
- Legal and tax counsel managing multi-location Korean operations
The short answer
A foreign corporation's business year is its accounting period for Korean tax purposes, capped at 12 months, and it only matters for foreign corporations taxed on a comprehensive, self-assessed basis — it's irrelevant for corporations subject only to withholding.
- If a foreign corporation with a Korean place of business has no business year specified in its governing documents, it must separately declare one, together with its place-of-business establishment filing or business registration, within 2 months of establishing that place of business.
- If it has real estate income or real estate transfer gains but no Korean place of business, it must declare a business year within 1 month of first earning that income.
- If it fails to declare a business year at all, Korea defaults to a calendar year (January 1 – December 31).
A foreign corporation's tax domicile is generally the location of its Korean place of business — or, without one, the location of the relevant real estate or asset.
Quick comparison
| Situation | Business Year Deadline | Default If Not Declared |
|---|---|---|
| Korean place of business, no business year in governing documents | Within 2 months of establishing the place of business | Calendar year (Jan 1 – Dec 31), with the first year running from establishment to Dec 31 |
| Real estate income / real estate transfer gains, no Korean place of business | Within 1 month of first earning that income | Same calendar-year default applies |
| Changing an existing business year | Within 3 months of the end of the prior business year | Business year is treated as unchanged |
| Losing the Korean place of business mid-year | N/A (automatic) | The period from the start of that business year to the date the place of business is lost becomes a single, standalone business year |
Understanding business year rules
When a business year must be separately declared
A foreign corporation with a Korean place of business, whose governing law or articles don't specify a business year, must set one and report it — together with its place-of-business (branch) establishment filing or business registration — to its jurisdictional tax office. This filing is due within 2 months of the date the place of business was established.
A foreign corporation without a Korean place of business, but with Korean-source real estate income or gains on the transfer of real estate, must separately declare a business year within 1 month of the date that income first arose.
Why it only matters for some foreign corporations
The business year concept is meaningful only for foreign corporations taxed on a comprehensive, self-assessed basis — because corporate tax is calculated per business-year period for those entities. For foreign corporations subject purely to withholding and separate taxation, the concept of a business year has no practical significance, since there's no periodic return being filed against it.
Changing a business year
A foreign corporation that wants to change its business year must notify its jurisdictional tax office within 3 months of the end of its prior business year. If that notification isn't filed within the deadline, the business year is treated as unchanged.
Worked example. Consider a Korean branch aligning its fiscal year with a new global reporting calendar:
- Current FY: May 1, 2025 – April 30, 2026
- Transitional FY (short period): May 1, 2026 – December 31, 2026
- New FY: January 1, 2027 – December 31, 2027
Because the eight-month transitional period is treated as its own standalone business year — the same "deemed business year" logic described above for a mid-stream fiscal year change — it requires its own, separate corporate tax return, distinct from the return covering the year before it and the one covering the year after.
Since a Korean corporate tax return is due within 3 months of the relevant business year's end, this timeline produces three separate filing deadlines:
| Period | Corporate Tax Return Due Date |
|---|---|
| Current FY: May 1, 2025 – April 30, 2026 | July 31, 2026 |
| Transitional FY (short period): May 1, 2026 – December 31, 2026 | March 31, 2027 |
| New FY: January 1, 2027 – December 31, 2027 | March 31, 2028 |
The short transitional period doesn't get folded into either the year before or after — it stands alone, with its own filing obligation and its own deadline.
Deemed business years
Korean law fills in several scenarios where a business year isn't cleanly defined:
- No business year reported at all (for a foreign corporation with a Korean place of business, and no provision in its governing documents): the business year defaults to January 1 through December 31. The first business year, however, runs from the date the place of business was established (or the date real estate income/transfer gains first arose) through December 31 of that year.
- Losing the Korean place of business mid-year: the period from the start of that business year until the date the place of business is lost becomes a single, standalone business year.
- Real estate income or transfer gains ceasing (for a foreign corporation without a Korean place of business) that reports this change to its tax office: the period from the start of that business year to the date of that report becomes a single, standalone business year.
- A business year change: the period from the start of the prior business year to the day before the new business year begins becomes a standalone business year — unless that period is under 1 month, in which case it's folded into the new business year instead.
Understanding tax domicile rules
The general rule
A foreign corporation's Korean tax domicile — the location that determines which tax office has jurisdiction — is generally the location of its Korean place of business. Where a foreign corporation has no Korean place of business but has real estate income or real estate/asset transfer gains, tax domicile is instead the location of that asset (the real estate, or the asset/right being transferred).
Tax domicile matters because virtually all corporate tax filing and payment obligations — except where the law specifically provides otherwise — run through the jurisdictional tax office at the company's tax domicile. It carries real weight specifically for foreign corporations that file comprehensively: those with a Korean place of business, or with real estate income or real estate transfer gains.
Multiple places of business
Where a foreign corporation has two or more Korean places of business, its tax domicile is the location of its primary place of business — generally, the location with the highest business revenue in the prior business year. This determination is made only once, at the point tax domicile is first established, not re-evaluated every year.
Special cases: construction and similar businesses
For a foreign corporation in construction or a similar business whose Korean place of business is located in territorial waters (making that location impractical as a tax domicile), the domicile instead defaults to the location on the corporate registry. If there's no registered location either, the domicile is the place where the business's operations are centrally managed within Korea.
Tax domicile designation by the authorities
In two situations, the regional tax office (or, where jurisdiction shifts, the National Tax Service) may designate a foreign corporation's tax domicile directly:
- Where a foreign corporation has two or more Korean places of business and its primary place of business can't be determined
- Where a foreign corporation has no Korean place of business, has two or more assets generating real estate income or real estate/asset transfer gains, and fails to report its tax domicile within 1 month of the date those multiple sources of income arose
In either case, the tax authority must notify the company of the designation within 45 days of the business year-end; if it fails to notify within that window, the company's previous tax domicile remains in effect by default.
Changing tax domicile
If a foreign corporation's tax domicile changes, it must notify the new jurisdictional tax office within 15 days of the change. If a foreign corporation no longer has a Korean place of business or Korean-located assets at all, it must separately report that fact to its (former) jurisdictional tax office.
Practical insight: missing the business year declaration doesn't mean no business year — it means the default applies
Companies sometimes treat the business year declaration as optional paperwork that can be sorted out later. In practice, missing the deadline doesn't leave the business year undefined — Korea simply applies the calendar-year default, which may not match the fiscal year the parent company actually uses for consolidated reporting. Aligning the Korean business year with the global fiscal year, where that's the intent, has to happen through the declaration — it doesn't happen automatically.
Practical insight: tax domicile determinations are sticky
The "primary place of business" determination for multi-location foreign corporations is made only once — the first time tax domicile needs to be established — based on that year's revenue figures. A branch's revenue mix can shift substantially in later years without changing which location remains the official tax domicile, which is worth knowing before assuming domicile automatically follows wherever current revenue happens to be concentrated.
What foreign companies often get wrong
- Assuming the Korean business year automatically matches the parent company's global fiscal year without filing a separate declaration.
- Missing the 3-month deadline to report a business year change, resulting in the business year being treated as unchanged despite the company's intent.
- Assuming tax domicile is re-evaluated periodically based on current revenue, when the "primary place of business" determination is generally made only once.
- Failing to report a change in tax domicile within 15 days, or failing to report the loss of a Korean place of business or Korean assets altogether.
Frequently asked questions
Does every foreign corporation need to declare a business year?
No — it's only relevant for foreign corporations taxed on a comprehensive, self-assessed basis (those with a Korean place of business, real estate income, or real estate transfer gains). Foreign corporations subject purely to withholding don't need one.
What happens if we never declare a business year at all?
Korea defaults to a calendar-year business year (January 1 – December 31), with the first year running from the date the Korean place of business was established, or the date real estate income first arose, through December 31 of that year.
Can our Korean business year differ from our head office's fiscal year?
Yes, in principle — the Korean business year is set independently through the declaration (or defaults to the calendar year if not declared), and doesn't have to match the parent's fiscal year unless the company actively aligns them.
If we have offices in two Korean cities, which one is our tax domicile?
Generally, the one with the higher business revenue in the prior business year — determined once, at the point tax domicile is first established, not reassessed annually as revenue shifts.
What if the tax authority designates our tax domicile and we disagree?
The designation process includes a notification requirement — the authority must notify the company within 45 days of the business year-end. If you believe the designation is incorrect, this is a point to raise with your jurisdictional tax office directly, as domicile affects which office has filing jurisdiction going forward.
Practical checklist
For foreign corporations establishing or restructuring Korean operations, confirm:
- Whether your Korean place of business's governing documents already specify a business year, or whether a separate declaration is required
- The 2-month (place of business) or 1-month (real estate income) deadline for declaring a business year has been calendared
- Whether you intend to align the Korean business year with headquarters' fiscal year, and have filed the declaration accordingly
- Any business year change is reported within 3 months of the prior business year's end
- Your tax domicile — and, if you have multiple Korean locations, which one qualifies as primary — is correctly identified with your jurisdictional tax office
- Any change in tax domicile, or loss of a Korean place of business or assets, is reported within the applicable deadline
Key takeaways
Business year and tax domicile are procedural questions, but both carry firm deadlines and default outcomes that apply automatically if those deadlines are missed. For any foreign corporation filing comprehensively in Korea — because it has a Korean place of business, real estate income, or real estate transfer gains — getting these two administrative points right from the outset avoids downstream friction with fiscal-year alignment and jurisdictional filing questions later.
Related guides
- How Is a Foreign Corporation Taxed in Korea? The Corporate Tax Framework Explained
- What Income Is Taxed for Foreign Corporations in Korea, and How?
- How to Register a Korean Branch or Liaison Office: A Step-by-Step Guide
- Corporate Income Tax Compliance for Foreign Companies in Korea (coming soon)