In Japan, an applicant may file a divisional patent application (in accordance with Patent Act Art. 44). This is possible from the filing of the application until prescribed deadlines.

When is the latest I may file a divisional application after the JPO grants my patent?

The JPO's Decision to Grant a Patent transmittal date triggers a thirty-day window for filing a divisional application. By the end of the thirty days the applicant must file any divisional application(s) desired. Please note that this is only viable for applications that was filed after April 1, 2007. (Most likely this applies to yours, but be sure to check!)

Please note that a divisional application must be filed within 30 days from the transmittal date of the Decision to Grant a Patent and before the registration fee is paid. Once you have paid the Issue Fee, it is not possible to file a divisional application, so at the latest the divisional application needs to be filed along with the Issue Fee payment.

But, you may ask,

Can I somehow extend the divisional application deadline?

Yes, in the case that a Decision to Grant Patent is issued, is possible to push off the deadline to pay the registration fees by filing a 30-day extension. This also prolongs the deadline to file a divisional application(s), provided that the divisional application is filed before completion of payment.

How about if I receive a Final Decision of Rejection?

If a patent is rejected, the deadline is different. Instead, if the applicant files an Appeal to the Final Decision of Rejection, then at that same time he or she may file a divisional application. This is allowed up to four (4) months from the issuance of the Final Decision of Rejection. Once an Appeal is filed, divisional applications may not be filed.

Beyond this, it would be good to consult a Japanese patent attorney for more specific details of a divisional application one is considering.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.