Tips for Filing Divisional/Continuation Applications in China Versus the United States

“As its economy has rapidly developed, China has become one of the most frequently selected countries for foreign patent filings. However, due to different rules governing divisional applications (DAs), an applicant who attempts to re-use their DA strategy in China as they did in the United States will be sorely disappointed.”

China-US - the past decade—and likely for the rest of our lifetimes—China has become a favored venue for patent filings due to its increasing GDP and expansive market. However, U.S. applicants familiar with U.S. patent rules should be careful not to employ the same prosecution strategies as used in the United States when filing Chinese patents, as the rules in the two jurisdictions are materially different. For example, in the United States, it is common to file a string of continuation applications for inventions that are licensing/litigation worthy. In China, there is no corresponding opportunity.

Divisionals at the USPTO

Within a maximum 20-year span, patent applicants may continually file divisional applications (DAs) at the U.S. Patent and Trademark Office (USPTO), provided the next filed DA is co-pendency with another family member (practitioners in China often refer to a “divisional” application in the same way U.S. practitioners refer to a “continuation” application. Of course, in the United States, continuation applications and divisional applications are both types of “continuing” applications, with a divisional application most often being filed in response to an earlier Restriction Requirement (U.S. practice) or lack of Unity of Invention (International practice). For purposes of this article, there is no significant distinction made between the terms “divisional” and “continuation”, and I refer generally to “DA”). While the family members share a common specification, the applicant may include different claims in each DA, provided the specification provides adequate support of the claims. Accordingly, in the United States, an initial application that is rich in pioneering features and ideas provides the applicant with the opportunity to decide later whether those features and ideas have sufficient commercial value to justify another DA. This can be especially valuable in technology fields where it takes time before the market develops, or in technologies where it takes some time for a standards-setting-organization to adopt a standard. U.S. applicants who are innovators in these technologies are quite familiar with the approach of serially filing a string of DAs that incrementally hone-in on claims that are essential to the adopted standard or commercially essential to the technology adopted by the market.

As its economy has rapidly developed, China has become one of the most frequently selected countries for foreign patent filings. However, due to different rules governing DAs, an applicant who attempts to re-use their DA strategy in China as they did in the United States will be sorely disappointed. The differences in DA rules are absolutely worth an applicant’s attention when protecting their inventions in China.

Claiming Domestic Priority

From a prosecution standpoint, a CIP (Continuation-In-Part) application is not a viable option in China because adding new subject matter to the specification, outside of the original scope of the basic parent specification, is not permitted. However, there is a process called “claiming domestic priority”, which allows a new application to be filed that contains new subject matter. This new application should be filed within 12 months from the date the basic application was filed to the Chinese National Intellectual Property Administration (CNIPA). This process is suitable for invention or utility model applications, not including design applications. Notably, if an applicant invokes “claiming domestic priority”, the basic application will be considered to be withdrawn in response to the newly application containing the domestic priority request.

From a DA filing timing standpoint, the rules are different before and after the basic application has been granted or rejected. Before the basic application is granted or rejected, a DA can be filed at will, and so, in this time period, the rules in China are the same as they are in the United States. However, unlike in the United States, after the basic application has been granted or rejected, a DA may no longer be filed.

Illustrating the Differences

Figures 1 and 2 provide examples that help illustrate the contrast between Chinese and American DA rules:  Fig 1 shows allowable DA timing in the United States, while Fig 2 shows allowable DA timing in China. In the Figures, horizontal arrows represent pendency of respective patent family members, and vertical arrows represent (i) a timing of filing a DA, and (ii) a claim to priority.

As seen in Fig 1, in the United States, before the basic application is granted or rejected (represented by everything to the left of the red vertical line), a DA can be filed that claims priority to the basic application because the DA will be co-pending with the basic application. For example, application A and B are DAs from the basic application. Application B itself may be the parent of a further DA (application C) because they co-pending, and for the relationships between these two applications (B and C), the pendency of the basic application is not relevant, although in this example, the basic application happens to still be pending.

Still in Fig 1, in the period during or after the basic application has been granted or rejected (represented by everything on and to the right side of the red vertical line), the application B is able to be the parent of another DA (application E), and application C is also able to be a parent of a further DA (application D). Furthermore, application E is able to be the parent of yet another DA (application F) and so on, so that the patent family can be extended without limit, during the 20-year window of time triggered by the filing of first filed utility application.

Fig 1. DA timing according to U.S. patent rules

In comparison, in Fig 2, according to Chinese patent rules, as seen on the left side of the red vertical line, a DA can be filed from the basic application (application A’, application B’), and the application B’ is parent another DA (application C’). After the basic application is granted or rejected (at the right of the red line), no further DAs may be filed, and so regardless of the status of child application A’ or grandchild application C’, no further DAs may be filed.

Fig 2. DA timing according to Chinese patent rules

A brief summary and comparison of DA rules between China and the United States is shown in Table 1.

Table 1. Comparison of DA rules between China and the United States

Considering the timing differences between the two countries, if an applicant receives a Notice-of-Allowance (NOA) for the basic application from the CNIPA, or the basic application been rejected from the CNIPA, the applicant should be aware that before the NOA or the rejection becomes effective, this is the last opportunity to file a DA. Also, when applicant receives a NOA of a DA from the CNIPA, it is important to be mindful whether the basic application has been granted or rejected. If the basic application has been granted or rejected, a further DA cannot be filed; otherwise, a further DA can be filed.


Sometimes the decision whether to file a DA in China is unclear. In such situations, it is best to file a DA with simple claims first before the due date in order to meet the deadline for submitting a new DA, then amend the claims afterwards by a voluntary amendment. This strategy can postpone the decision time without missing an opportunity to file a DA. The new DA can be abandoned if the applicant determined filing a new DA is not necessary.However, does this mean that after the basic application is granted or rejected it is absolutely impossible to file a further DA? The answer is technically “yes’, but practically “no”.

A “passive DA process” according to the CNIPA patent rules permit some opportunity to extend the filing opportunities of serial DAs. According to this process, when the application contains two or more inventions which have no clear relation to each other, the examiner may issue a Unity Defect, allowing the applicant to file a DA. In this regard, a Unity Defect from the CNIPA is similar to a Restriction Requirement from the USPTO under 35 U.S.C. 121. The basis of a Unity Defect is that each claim in the set of claims does not share a common technical feature. The main situations that give rise to a Unity Defect (cited from CNIPA Guidelines For Patent Examination) are: (1) The original claims contain two or more inventions that do not meet the requirement of unity; (2) There is no unity between a claim or replacement independent claim introduced in an amendment to the application and the invention defined in the original claims; or (3) One of the independent claims lack novelty or inventive step, and there is no unity between the other claims. In view of this opportunity, it may be in the applicant’s best interest to cultivate a Unity Defect, so as to prolong the period by which an applicant may file a “last” application that is entitled to the earlier filing date of the basic application. Moreover, these rules permit an application to file a divisional application off of another divisional application provided the examiner indicated that the claims in the parent divisional application had a Unity Defect. Accordingly, with appropriately planned claim sets added to a new divisional application, it is feasible to perpetuate a patent family well beyond the pendency of the first patent application in the family.

Practice Points

The following are suggestions regarding how to fabricate a Unity Defect in order to make a further divisional application after the basic application is granted according to Unity Defect rules:

  1. At the time of receiving a NOA from CNIPA for the basic application, file a divisional application as a tactical step prior to paying the issue fee.
  2. Include in the divisional application at least two or two groups of independent claims, each of which including multiple independent claims that have a similar claim scope, although of differing statutory class. For example, in addition to a device claim, consider adding a method of using the device, a corollary device which claims a method of using of the corollary device claim, etc.
  3. The independent claims of the two or more groups should have separate specific technical features which make the two or two groups different from each other, not only for literally different, but also substantively different.
  4. In most situations, the examiner ascertains the Unity Defect requirement before making a prior art search, without evaluating the novelty of the claims. Accordingly, the two or more groups of independent claims should be drafted so the claim sets are objectively literally different and substantively different from conventional prior art point of view.

As a practical example, consider the following two cases:

Case 1, independent claim 1 includes 3 elements: X, Y, and Z; and independent claim 2 includes 3 elements: X’, Y’, and Z’. Elements “X, Y, Z” and element “X’, Y’, Z’” have similar meanings. The patent examiner may ascertain claim 1 and claim 2 are the same technical solution, leading to no Unity Defect;

Case 2, independent claim 1 includes 4 elements: X, Y, Z, and O; and independent claim 2 includes 4 elements: X’, Y’, Z’, and P. Element O and element P are separate novelty features. Thus, claim 1 and claim 2 do not have similar or corresponding specific technical features, and so a Unity Defect OA maybe properly be triggered.

Carefully Cultivate Your Claims

As shown above, in China, your opportunities for filing a continuation extinguish after the basic application has been granted or rejected. This greatly limits an applicant’s ability to observe market developments before filing a refined set of claims that are relevant to that market. However, if the applicant prepares an initial set of claims that “encourages” the examiner to issue a “Unity Defect”, applicants are afforded an extended term by which to see additional patents. Thus, in China there is no per se right to file a family of continuing applications that are strung together as co-pending applications. There is however the opportunity to file a set of claims that encourages the examiner to issue a unity rejection in the original application and/or a divisional application. In the case that the unity rejection is issued in a divisional application, the applicant may file another divisional application no later than the expiration of two months from the date of receiving a Notification to Grant Patent Right to the divisional application. Accordingly, careful cultivation of claim sets that have a unity defect provides the opportunity to file a serial string of divisional applications that can extend well past the pendency of the original patent application.


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Copyright: trambo 


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2 comments so far.

  • [Avatar for weibin.shi]
    August 2, 2019 05:57 am

    thank you. i really hope the article helps.

  • [Avatar for JTS]
    August 1, 2019 06:51 pm

    Thank you, excellent explanation.