Divisional applications are one of the most heavily used post-filing tools in Korean patent practice. They sidestep unity-of-invention rejections, let you fast-track core claims while keeping the rest alive, and let you pick up new claim sets as the market changes. A divisional retains the original filing date — so priority is preserved — but missing the available windows or stepping outside the original disclosure can cause the divisional itself to be rejected.
What a divisional is
Patent Act Article 52 provides that "when two or more inventions are filed in a single application, part of them may be divided into one or more separate applications within the matter described in the original specification or drawings." A divisional is deemed to have been filed on the original filing date, so prior-art reference dates remain unchanged. This also means you cannot inject new ideas at division time — only inventions already disclosed in the original spec qualify.
Three filing windows
Article 52(1) defines three windows in which a divisional may be filed. Miss the window and the divisional is rejected, so each phase of prosecution should keep the next window in mind.
- During the amendment-eligible period: typically the response window for an office action under Article 47(1)
- Within 3 months of a rejection decision: counted from service of the rejection-decision notice
- Within 3 months of a granting decision (or appeal-board reversal): counted from service of the relevant notice
| Window | Trigger | Primary use |
|---|---|---|
| Amendment-eligible | OA response time | Cure unity rejections, restructure claim sets |
| 3 months post-rejection | Service of rejection decision | Pair with re-examination request |
| 3 months post-grant | Service of granting decision | Spin off remaining claims for follow-on rights |
Four practical strategies
1) Cure unity-of-invention rejections
If the examiner cites lack of unity (Patent Act Article 45) — claim group A and claim group B are unrelated inventions — leaving one group in the parent and moving the other into a divisional keeps both alive. Filing fees double, but accepting the unity rejection forfeits the non-elected group permanently. This is the single most common reason to file a divisional in Korea.
2) Fast-track the core claims, divisional the rest
If you need core claims granted quickly for licensing or enforcement, narrow the parent to those claims at the OA response stage and move the rest into a divisional. The divisional has its own examination cycle and takes longer, but the parent reaches grant earlier and you keep both right portfolios.
3) Catch up to market changes — follow-on rights
When market evolution makes claims that were peripheral at filing critically important, file a divisional within three months of the granting decision to dial in the new claim language. Remember that the divisional must stay within the original specification — the door is only open if you wrote the spec broadly enough at filing time.
4) Layered defense across infringement scenarios
Pairing a "narrow-and-strong" claim set with a "broad-and-weak" set lets you assert the right claim against each infringement scenario. A divisional that splits these into separate cases creates a layered defense — even if one set is killed by invalidation, the other survives.
What divisionals can't do
The three windows above are exhaustive — there is no "any time before grant" rule like the US continuation. Filing fees, examination-request fees, and registration fees all duplicate. The 3-months-post-grant window also overlaps with the registration-fee deadline, so calendar discipline matters: miss the registration fee and the right vanishes; miss the divisional window and follow-on rights are gone.
Korea vs. US continuations
The US has divisionals plus continuations and continuations-in-part (CIP), giving more flexibility than Korea. According to the USPTO MPEP, continuations can be filed any time the parent is still pending — looser timing than Korea. For multi-country prosecution, track Korean divisional windows and US continuation deadlines on a single calendar.
- Statute
- Patent Act Article 52
- Window 1
- Amendment-eligible period
- Window 2
- 3 months post-rejection
- Window 3
- 3 months post-grant
- Filing date
- Inherits parent date priority preserved
Frequently asked questions
Can I add new ideas to a divisional?
No. Only matter already disclosed in the parent's original specification and drawings is eligible. New ideas need a fresh application — but that loses parent priority. This is why generous spec drafting at filing time is the real precondition for using divisionals strategically.
Can a divisional get expedited examination?
Yes. A divisional is treated as its own application, so if it meets the expedited examination criteria, you can request expedited treatment. A common pattern in pre-licensing situations: move the core claim set to a divisional and request expedited examination there.
How much does a divisional cost?
Filing, examination, and registration fees all duplicate. Attorney work, however, is usually less than a brand-new draft because the spec is already in place — typically about 60-70% of new-application cost. When the strategic value is clear (core-claim split, follow-on rights), the ROI is strong.
File a Korean divisional with iphere
Unity rejections, post-grant follow-on rights, and expedited examination on divisionals — handled in one workflow with calendar reminders for each window.