Korea Domestic Priority Claim for Foreign Corporate Patent Applications: What to Verify in Practice
When a foreign corporation files a patent in Korea and wants to claim domestic priority, the subsequent application must be filed within one year of the earlier application date.
This applies to foreign corporations that have already filed a patent or utility model application with the Korean Intellectual Property Office (KIPO). It differs from a treaty-based priority claim because it is grounded in the Korean application — not the home-country application.
This article covers the requirements for a domestic priority claim, how it differs from treaty priority, the points foreign corporations most often miss in practice, and the required documents and procedures.
What Is a Domestic Priority Claim?
A domestic priority claim is grounded in Article 55 of the Korean Patent Act.
It allows an applicant who has already filed an invention in Korea to file a follow-on application within one year — supplementing or improving the earlier disclosure — while retaining the filing date of the earlier application.
In practice, this is most often used when additional experimental data emerges after the initial filing, or when the applicant wants to broaden the scope of claims.
How Does It Differ from Treaty Priority?
Treaty priority is the mechanism under the Paris Convention used when filing in Korea based on a home-country application (such as the United States, Japan, or China).
Domestic priority, by contrast, is used when a Korean application serves as the basis for a subsequent Korean application.
This is exactly where foreign corporations are most likely to get confused.
The simplest framing: home-country filing → Korean filing is treaty priority, while Korean first filing → Korean second filing is domestic priority.
Who Can File?
The applicant of the earlier application and the applicant of the later application must be the same.
If a foreign corporation files the earlier application under its Korean subsidiary's name and the later one under the headquarters' name, the priority claim will not be recognized as-is.
In that case, a change-of-applicant filing must be submitted in advance to preserve the priority claim.
The 12-Month Deadline Foreign Corporations Often Miss
Once one year (12 months) has passed from the earlier filing date, a domestic priority claim is no longer possible.
The most common bottleneck in practice is when decision-making among the headquarters, foreign law firm, and Korean agent drags on, and the matter only reaches the Korean agent in the eleventh month.
| Item | Deadline | Notes |
|---|---|---|
| Earlier filing date | Day 0 | Based on KIPO receipt date |
| Domestic priority claim window | 1 year | Patent Act Article 55 |
| Period to amend the priority claim | 1 year 4 months from the later filing | Amend with care |
| Date the earlier application is deemed withdrawn | 1 year 3 months from the later filing | Automatically withdrawn |
Caution: The earlier application is deemed withdrawn once 1 year and 3 months have passed from the later filing date. If your goal is to keep the earlier application alive, the decision to claim domestic priority requires careful consideration.
When the Home-Country Priority Period Overlaps
A common scenario is filing first in the home country, entering Korea via treaty priority, and then filing a supplementary application using domestic priority.
In that case, the deadline is measured from the Korean earlier filing date, not the home-country filing date.
Calculating the period from the home-country date will cause you to miss the deadline outright.
Unity of Invention and Additional Embodiments
Adding new embodiments or improvement inventions to the later application is permitted.
However, content that is not described in the earlier application takes the later filing date as its effective date, and only content already present in the earlier application is back-dated to the earlier filing date.
A weak separation between these two will surface immediately at the office action stage.
The Domestic Priority Claim Procedure
The procedure itself is straightforward, but foreign corporations regularly get stuck at the power-of-attorney and translation stages.
| Step | Content | Responsible Party |
|---|---|---|
| 1 | Review of the earlier specification and drawings | Korean agent |
| 2 | Drafting the later specification (with priority claim notation) | Korean agent |
| 3 | Preparation of power of attorney (apostille or notarization) | Foreign corporation |
| 4 | Electronic filing with KIPO | Korean agent |
| 5 | Verification of the priority claim statement and earlier application number | Korean agent |
What Must Be Stated in the Application
- A statement that priority is being claimed
- The application number of the earlier application
- The filing date of the earlier application
- Whether the earlier filing is a patent application or a utility model application
If even one of these items is missing, the priority claim will not be recognized.
Under the Enforcement Rules of the Patent Act, these items must be stated at the time of filing, so adding them after filing is difficult. For the precise format, cross-check the Korean Intellectual Property Office notices and the original text of Article 55 of the Patent Act on the Korea Law Information Center.
Power of Attorney and Translation in Practice
When a foreign corporation appoints a Korean agent, the power of attorney must be an original signed in the home country.
Depending on the country, an apostille or consular authentication may also be required.
More often than the form of the power of attorney itself, who has signing authority becomes the issue. Having a branch manager sign without a board resolution can trigger a correction order later.
Practice Tip: When a Korean subsidiary exists, signature by the subsidiary's representative often allows the matter to proceed without a separate apostille. The choice between direct filing by headquarters and filing through the subsidiary should be reviewed alongside the future plan for transferring rights.
The exact power-of-attorney format and costs vary by case, and we will walk you through the specifics during a free consultation.
Request a free consultation now → 02-363-2251 / KakaoTalk: alexkorea
If more than eight months have passed since the earlier filing date, the schedule can get tight quickly — don't wait, reach out first.
Where Foreign Corporations Actually Get Stuck
More important than the paperwork is whether the earlier and later specifications are aligned.
When Specification Mismatches Break Priority
It is possible to add new claims in the later application that were not in the earlier one, but those portions do not receive the priority effect.
Priority is not granted to the later application as a whole — it is assessed on a claim-by-claim basis.
In actual examination, this is the single most common ground for refusal.
The Trap of Translating the Home-Country Specification Verbatim
A common pattern is to translate the home-country application directly, file it as the Korean earlier application, and then refine the claims in Korean style within one year while claiming domestic priority.
When this is done, content that was present in the home-country specification but omitted from the Korean earlier application receives no priority effect.
The earlier specification should be drafted broadly from the outset, with the later supplementation in mind.
Inconsistent Inventor Notation
If the inventor's name was entered as First/Last in the home country but in a different format in the Korean filing, a correction order can be issued.
Inventor notation in the earlier and later applications should be unified from the very start.
The Effect and Limits of the Priority Claim
When priority is recognized, the assessment date for novelty and inventive step is back-dated to the earlier filing date.
The patent term itself, however, is calculated from the later filing date.
Scope of the Priority Effect
- Novelty assessment: Based on the earlier filing date
- Inventive step assessment: Based on the earlier filing date
- Prior art status: Based on the earlier filing date
- Patent term start: Based on the later filing date
- Examination request period: 3 years from the later filing date
What Happens When Priority Is Denied
If there was a disclosure of the same or similar invention — by the applicant or a third party — during the intervening year, novelty disappears the moment priority is broken.
This frequently becomes an issue when there has been a conference presentation or product launch in the home country.
It may be possible to recover via the self-disclosure exception (Article 30 of the Patent Act), but the requirements are strict and case-by-case review is needed.
Required Document Checklist
- Proof of the earlier application number and filing date
- A copy of the earlier specification and drawings
- The later specification, claims, and drawings
- Power of attorney (signed by headquarters, with apostille if required)
- Corporate register or Certificate of Incorporation
- Inventor list (with English and Korean notation unified)
- Assignment from inventor to corporation (depends on home-country law)
Caution: In the United States and some European countries, the structure is such that the individual inventor is the applicant, so when filing in Korea, a separate inventor-to-corporation assignment may be needed. Since this varies by home-country jurisdiction, the headquarters IP team and the Korean agent need to align in advance.
Costs vary by case, and we provide accurate guidance during a free consultation.
Frequently Asked Questions (FAQ)
Q1. Can I use a domestic priority claim when filing in Korea based on a home-country application? No. A claim based on a home-country application is a treaty priority claim (Paris Convention); only a Korean earlier application can serve as the basis for a domestic priority claim. They are two separate systems.
Q2. The earlier application is a utility model — can I switch the later application to a patent and still claim domestic priority? Yes. Article 55 of the Patent Act recognizes the priority claim whether the earlier filing is a patent or a utility model. That said, claim drafting style differs, so prior review with your agent is necessary.
Q3. Once a year has passed, can I no longer file a supplementary application at all? A domestic priority claim is no longer possible. However, the rights strategy can be redesigned through a divisional application, a converted application, or a separate new filing. Whether each option applies depends on the specific case.
Q4. What happens to the earlier application once the later application is filed? The earlier application is automatically deemed withdrawn once 1 year and 3 months have passed from the later filing date. If you want to keep the earlier application alive, you'll need to either drop the priority claim or use a separate strategy.
Q5. If I file under the foreign headquarters' name but want to transfer the rights to a Korean subsidiary later, when should this be handled? Resolving the applicant's identity before filing is the cleanest approach. Post-filing transfer differs in procedure and cost depending on whether it occurs before or after registration. The right timing should be confirmed through consultation.
Q6. Can I combine PCT filings with domestic priority? Yes. Common sequences include Korean earlier application → PCT application with priority claim, or Korean earlier application → later application with domestic priority claim → PCT application. The deadline calculations get complex, so up-front planning is essential.
Need a Specialist Consultation?
Patent applications by foreign corporations with domestic priority claims involve deadline management, specification alignment, and power-of-attorney formalities — all tangled together.
If more than six months have passed since the earlier filing date, or if there are differences between the home-country and Korean specifications, prompt review is necessary.
VISION Administrative Office handles the full scope of foreign corporations' entry into Korea (entity formation, visas, foreign-investment notifications, and intellectual-property-related administrative procedures), and at the patent-filing stage we coordinate end-to-end through our partner network of patent attorneys.
VISION Administrative Office
- Phone: 02-363-2251
- Email: 5000meter@gmail.com
- Address: (04614) 3F Seongwoo Building, 324 Toegye-ro, Jung-gu, Seoul
- KakaoTalk consultation: alexkorea
Costs vary by case, and we provide accurate guidance during a free consultation. If your earlier filing date is approaching, don't wait — reach out first.
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