Executive summary
A Korean branch of a foreign company may deduct certain expenses incurred by its foreign head office or other related offices when calculating its Korean taxable income. But the deduction is not automatic.
Under Korea's corporate tax rules, expenses must be reasonably related to Korean-source income and reasonably allocated to the Korean permanent establishment. Where common expenses are incurred by the head office or another related office, Korea provides specific rules for determining which portion may be allocated to the Korean branch.
The rules generally focus on two questions:
- Is the expense reasonably related to the Korean business?
- If so, how much of the expense should be allocated to Korea?
For common expenses, the allocation is based on the Korean branch's relevant revenue compared with the revenue of the related offices worldwide, with the relevant revenue being the business or commercial revenue considered related to the expense being allocated.
For Finance and Tax teams, however, the calculation itself is only part of the issue. The numbers used in the allocation need to be supportable and consistent with the underlying head-office records. If, for example, revenue is used as the allocation key, a difference between the revenue reported by the foreign head office and the revenue used in the Korean branch's allocation calculation can become an obvious question during a Korean tax audit.
Who should read this
- Foreign companies operating a Korean branch or permanent establishment
- Regional and global Finance teams supporting Korean branches
- In-house Tax Managers responsible for Korean corporate tax filings
- Finance teams preparing head-office expense allocations
- Companies reviewing Korean branch positions before a tax audit
- Tax teams reviewing whether historical expense allocation documentation is sufficient
The short answer
A foreign company's Korean branch can generally deduct an appropriate portion of head-office or related-office expenses when those expenses are reasonably related to the Korean-source income of the Korean business.
However, the deduction is subject to Korea's expense allocation rules. In particular:
A Korean branch should not simply deduct whatever amount the head office charges or allocates to Korea. The expense must first be connected to the Korean business, and the portion allocated to Korea must be determined under the applicable allocation rules.
The Korean tax guidance specifically recognizes that expenses incurred by an overseas head office or related branch may be deductible where they are reasonably related to the Korean-source income. This makes the allocation methodology and supporting documentation just as important as the amount ultimately claimed as a deduction.
Quick comparison
| Issue | What the Korean rules focus on | Practical question |
|---|---|---|
| Local expenses | Whether the expense is related to Korean-source income | Is the expense actually connected to the Korean business? |
| Head-office expenses | Whether the expense is reasonably related to the Korean business | Does the Korean branch benefit from or relate to the expense? |
| Common expenses | Allocation under prescribed rules | What allocation key should be used? |
| Allocation amount | Relevant worldwide expense × applicable allocation ratio | Can the underlying numbers be substantiated? |
| Foreign currency | Conversion using the applicable annual average exchange rate | Was the correct exchange-rate methodology used? |
| Documentation | Supporting information for the expense and allocation | Can the branch explain the calculation during an audit? |
The underlying rules provide that expenses incurred by a foreign head office or related office may be deductible where they are reasonably related to Korean-source income, and that the allocation method is prescribed under the Corporate Tax Act and its regulations.
Understanding the allocation rules
Why can a Korean branch deduct head-office expenses?
A Korean branch is not treated as though every expense recorded in Korea is automatically deductible. For a foreign corporation, deductible expenses are generally limited to expenses that are related to Korean-source income and can reasonably be allocated to that income.
This is important because many of the costs supporting a Korean branch's business may actually be incurred outside Korea. For example, a foreign head office may perform planning, support, supervision, analysis, statistical, management, or other functions connected with the Korean business. The Korean tax guidance specifically recognizes the head office as a related office performing these types of functions for the Korean business.
Therefore, the fact that an expense was incurred outside Korea does not, by itself, prevent the Korean branch from claiming an appropriate deduction. The key issue is whether the expense is reasonably related to the Korean-source income.
What expenses can be allocated to Korea?
The relevant expense pool consists of management and general administrative expenses incurred by the relevant head office or related offices that are reasonably considered to relate to obtaining industrial or commercial profits from the Korean permanent establishment. There is an additional condition: the expense must be deductible under the tax law of the country where the expense arose.
This means that the starting point is not simply the entire head-office cost base. Instead, the analysis is essentially: which head-office or related-office expenses are reasonably connected to the Korean business? Only then should the allocation calculation be performed.
How is the common expense allocation calculated?
The Korean tax guidance provides an allocation mechanism for common expenses incurred by related offices. The basic concept is:
Korean allocation = Allocable common expenses × Korean relevant revenue / Worldwide relevant revenue
The relevant revenue is not necessarily every item appearing in the group's financial statements. The guidance refers to industrial or commercial revenue considered to have arisen in connection with the expenses being allocated.
This point is important. A company should not assume that total worldwide revenue is automatically the appropriate denominator for every expense pool. The revenue measure should be connected to the expense being allocated.
The allocation key matters
Consider a simplified example. A foreign head office incurs a pool of management expenses that is considered relevant to its various branches around the world. If the allocation methodology uses revenue, the Korean branch's share is determined by reference to the relevant Korean revenue compared with the relevant revenue of the related offices worldwide.
The important point is not simply the final percentage. The Tax team should be able to explain:
- What expenses were included in the allocation pool?
- Why were those expenses considered relevant to the Korean business?
- Why was revenue selected as the allocation key?
- What revenue was included in the numerator?
- What revenue was included in the denominator?
- Where did each number come from?
That documentation becomes particularly important if the allocation is later reviewed by the Korean tax authority.
Don't confuse expense allocation with amounts charged by the head office
Another important distinction is between (A) allocating common expenses, and (B) treating a head-office charge as a deductible internal transaction expense.
The Korean rules provide specific treatment for internal transactions with the head office. Expenses are deductible only to the extent they are within the arm's-length range and are essential or reasonably related to the income attributable to the Korean permanent establishment. Certain financing-related expenses, including specified interest and guarantee transaction fees, are subject to separate limitations.
Therefore, an invoice or internal accounting entry from the head office does not, by itself, establish the amount deductible by the Korean branch. The underlying nature of the expense and the applicable Korean rules still matter.
Foreign currency conversion
Where expenses are incurred in a foreign currency, the Korean guidance provides a specific conversion method for calculating the allocation amount. The foreign-currency amount is converted into Korean won using the average basic exchange rate or arbitrage exchange rate for the relevant business year under the Foreign Exchange Transactions Act.
This is another reason to preserve the calculation rather than simply recording the final KRW amount in the tax return. A reviewer should be able to identify the path from the original foreign-currency amount, through the applicable exchange-rate methodology, to the KRW amount, and finally to the allocation calculation itself.
What happens in a tax audit?
This is where the distinction between "the calculation is correct" and "the calculation is defensible" becomes important.
A tax auditor reviewing a Korean branch's common-expense deduction may naturally work backwards — from the Korean deduction, to the allocation ratio, to the Korean revenue over worldwide relevant revenue, to the underlying head-office revenue and expense data. If the numbers do not reconcile, questions can follow.
For example, if the Korean branch used revenue as its allocation key but the foreign head office reported a different revenue figure to its own tax authority, the Korean tax authority may ask why the numbers are different. The existence of a difference does not necessarily mean that the Korean tax return is wrong — but the company should be able to explain the difference with contemporaneous records.
A difference may arise because the relevant amounts were determined at different reporting dates, financial closing dates, or tax reporting stages. The important point is not to invent a reconciliation after the audit begins. The company should be able to demonstrate why the numbers differ and why the number used for the Korean allocation is appropriate.
Practical insight: match the numbers to the head office's reported figures
This is one of the most important practical points for Finance teams. Suppose a Korean branch allocates head-office common expenses using revenue as the allocation key, showing Korean revenue of USD 100 million against worldwide revenue of USD 1 billion.
If the foreign head office's own records or tax reporting show a materially different amount of revenue, the Korean tax authority may ask why the numbers used for the Korean allocation do not match. This does not necessarily mean the taxpayer made an error — there may be legitimate reasons for differences, including reporting timing, financial closing dates, tax reporting periods, accounting treatment, or other reporting conventions. But the difference needs to be explainable and supported by documentation. From a tax-audit perspective, the problem is not that the two figures must always be identical — it is an unexplained difference. Because tax authorities exchange information across jurisdictions, differences between amounts reported in different countries can become an issue before or during a tax audit. Finance teams should retain a clear reconciliation running from the head-office reported revenue, to the revenue used for the Korean allocation, to an explanation for any difference — that reconciliation can be far more valuable during an audit than the final allocation percentage alone.
Practical insight: don't overlook international transaction reporting
A common practical assumption is that a movement of funds between a head office and its Korean branch "isn't really an international transaction" because the parties are technically the same legal entity. That assumption can be risky.
What foreign companies often get wrong
- Treating all head-office expenses as automatically deductible. The fact that an expense was incurred by the head office does not automatically make it deductible in Korea — it must be reasonably related to Korean-source income and allocated appropriately. Better approach: identify the expense pool first, and document why the relevant expenses relate to the Korean business.
- Focusing on the allocation percentage but not the underlying numbers. A 10% allocation ratio may look reasonable, but the real question is 10% of what, and based on which numbers — the underlying revenue and expense figures should be traceable.
- Assuming the Korean revenue figure does not need to reconcile to the head office's reported figure. This can create unnecessary questions during a tax audit. Better approach: prepare a reconciliation between the figures reported by the head office and the figures used in the Korean allocation calculation, and document any differences.
- Assuming a head-office/branch transaction is automatically outside international transaction reporting. The legal relationship between a foreign head office and its Korean branch should not be the sole basis for deciding whether a reporting form is required. Better approach: review the reporting obligation separately for each type of head-office/branch transaction.
- Keeping only the final tax-return number. A tax return may show only the final amount allocated to Korea, which is not enough to explain the calculation if questions arise later. Better approach: keep the underlying expense schedules, allocation key, source data, calculation, and reconciliation together.
Frequently asked questions
Can a Korean branch deduct expenses incurred by its foreign head office?
Yes, potentially. Expenses incurred by a foreign head office or related office can be deductible where they are reasonably related to Korean-source income and appropriately allocated to the Korean business.
Is every head-office management expense deductible in Korea?
No. The relevant expense must be reasonably related to the Korean business, and the applicable allocation rules must be satisfied. The rules specifically refer to management and general administrative expenses that are reasonably related to the Korean permanent establishment's industrial or commercial profits.
Can revenue be used as an allocation key?
Yes. The Korean guidance provides an allocation formula using the Korean branch's relevant revenue compared with the relevant revenue of the worldwide related offices. The relevant revenue is the industrial or commercial revenue considered related to the expense being allocated.
What if the Korean revenue used for the allocation differs from the revenue reported by the foreign head office?
The difference should not simply be ignored. There may be legitimate reasons for the difference, such as different reporting or closing timing, but the company should be able to explain and support the difference.
Does the head office need to charge the Korean branch for the expense?
Not necessarily. The relevant issue for common-expense allocation is whether the expense is reasonably related to the Korean-source income and how the applicable allocation rules apply. A separate analysis may be required for internal transactions with the head office.
How should foreign-currency expenses be converted?
For purposes of calculating the allocation amount, the Korean guidance provides for conversion using the annual average basic exchange rate or arbitrage exchange rate under the Foreign Exchange Transactions Act.
Practical checklist
Before filing the Korean corporate tax return, a Korean branch should consider the following:
Expense pool
- Have we identified which head-office or related-office expenses are reasonably related to the Korean business?
- Have we excluded expenses that do not satisfy the relevant requirements?
- Can we explain why each major expense category was included?
Allocation key
- What allocation key is being used?
- Is the relevant revenue actually connected to the expense being allocated?
- Can we reproduce the allocation calculation?
Source data
- Does the Korean revenue figure reconcile with the foreign head office's reported figures?
- Does the worldwide revenue figure reconcile with the underlying head-office data?
- Do we have an explanation for any difference?
- Are the total expenses used in the allocation traceable to the head-office records?
Foreign currency
- Was the prescribed annual average exchange-rate methodology applied?
- Can the KRW calculation be reproduced from the original foreign-currency amounts?
Filing and documentation
- Has the required common-expense allocation statement/schedule been submitted with the Korean corporate tax return?
- Do we retain the detailed expense listing?
- Do we retain the allocation methodology and calculation?
- Do we retain supporting documents for the allocation key?
- Have we separately reviewed whether any head-office/branch transactions trigger international transaction reporting?
Key takeaways
For a Korean branch, head-office expense allocation is not simply a tax-return calculation. It is a documentation exercise. The Korean rules allow appropriately related head-office and related-office expenses to be allocated to the Korean business, but the allocation needs to be supported by the underlying expense pool, allocation methodology, and relevant financial data.
For Finance teams, one practical principle is particularly useful: if a number is used to allocate an expense to Korea, know exactly where that number came from — and be prepared to reconcile it to the number reported by the foreign head office.
And before filing, do not overlook the compliance side. A defensible allocation is not just a reasonable percentage. It is a calculation that can be traced from the Korean tax return back to the head-office records and explained if the tax authority asks.
Related guides
- Corporate Tax Filing in Korea: What Foreign Companies With a Korean PE Need to Know
- How Is a Foreign Corporation Taxed in Korea? The Corporate Tax Framework Explained
- Korean-Source Income for Foreign Corporations: Interest, Dividends, Real Estate, and Business Income
- Korean-Source Income for Foreign Corporations: Personal Services, Capital Gains, Royalties, and Securities
- International Transaction Reporting Requirements in Korea: What Foreign Companies Must File
- Surviving a Korean Tax Audit: A Field Guide for Foreign-Invested Companies (coming soon)