After a European patent is granted, if it is opposed, how exactly should one respond to the 9-month opposition period and the Boards of Appeal proceedings? Do not misremember the 2026 deadlines for opposition and appeal.

A European patent being opposed does not mean the patent is invalid. After receiving the notice of opposition, the patent proprietor usually has 3 months to reply and may request an extension, but the extension requires a fee; after the Opposition Division issues its decision, the losing party may appeal to the Board of Appeal within 2 months. The 2026 time limit rules have not changed fundamentally, but missing a single deadline may cause the patent to be lost directly. The key milestones and response points are set out below in procedural order.

The opposition period is only 9 months, counted from the date of the grant announcement.

The opposition procedure at the European Patent Office (EPO) starts from the date of publication of the grant in the European Patent Bulletin. Under Article 99 of the European Patent Convention (EPC), any third party may file an opposition within nine months from the date of publication. Note that this nine-month period is a hard deadline—it cannot be extended, nor can it be postponed simply because the other party files on the last day. In practice, many Chinese companies encountering this for the first time assume that "just granted means no problem," only to suddenly receive an opposition notice in the eighth or ninth month and be caught off guard. We generally advise clients to conduct a stability assessment immediately after the patent is granted, especially for patents corresponding to core products, and to prepare response materials in advance rather than waiting until an opposition arrives to dig through the files.

The grounds for opposition cannot just be raised arbitrarily. Article 100 of the EPC limits them to a few categories: lack of novelty, lack of inventive step, lack of patentability, insufficient disclosure in the specification, and claims extending beyond the original application documents. In other words, the opponent cannot bring up "infringement" or "ownership of rights," as those are handled through separate proceedings. Understanding this point is crucial for assessing where the other side will focus its attack.

The response period is 3 months; it can be extended, but it will cost you.

The Opposition Division will forward the notice of opposition to the patent proprietor and require a reply within a specified time limit. This period is usually three months, counted from receipt of the notification of opposition. If three months is not enough, an extension can be requested, generally up to two months, but an extension fee must be paid. An extension is not a right but a request, and the Opposition Division may grant or refuse it. In practice, if the case is technically complex and requires supplementary experimental data or expert witnesses, we generally recommend submitting the extension request at least one month in advance rather than waiting until the last few days of the deadline.

The response should address each ground of opposition point by point—amend the claims where amendment is warranted, and submit evidence where evidence is needed. There is a common misconception here: some clients believe that "not amending the claims makes them look more confident," but in opposition proceedings, appropriately narrowing the scope of protection is often an effective strategy for preserving the patent. How exactly to amend depends on the degree of support in the original disclosure and the priority document—you cannot add features out of thin air.

Within 2 months after the objection department's decision, an appeal may be filed.

After the Opposition Division issues its decision, any party dissatisfied with it may file an appeal with the EPO Boards of Appeal within 2 months from the date of notification of the decision. Filing an appeal requires payment of an appeal fee, and a statement of grounds of appeal must be submitted within 4 months. These two time limits are separate: the 2-month period is for the notice of appeal, and the 4-month period is for the grounds. If the 2-month period is missed, the decision becomes final. If the 4-month period is missed, the appeal may be deemed withdrawn.

The appeal board procedure is more formal and slower-paced than the opposition division. In practice, it is common for an appeal to take two to three years from filing to a decision. For products with a short market window, this time cost must be factored in from the outset. If the product covered by the patent has a life cycle of only three to five years, the product may have been replaced by the time the appeal is decided, so whether it is commercially worthwhile to continue must be calculated together with the business team. For more on coordinating overseas procedures, please refer to the process notes on overseas intellectual property.

The 2026 deadline hasn't changed, but don't mix up the two deadlines.

The core time limits for EPO oppositions and appeals in 2026 remain: 9 months for opposition, 3 months for reply, 2 months for appeal, and 4 months for grounds of appeal. No amendments have been introduced to shorten or extend these periods. What is easily confused is "9 months" and "3 months": 9 months is the window for others to file an opposition, while 3 months is the window for the patent proprietor to reply—the two involve different parties and different starting points. Some clients also treat "2 months for appeal" and "4 months for grounds of appeal" as a single time limit, and as a result file only the notice of appeal without the grounds, leaving themselves in a very passive procedural position.

One more reminder: EPO time limits are generally calculated from the "date of delivery" plus a certain number of days, not from the date of issuance. The deemed delivery dates differ between electronic and paper delivery, so you need to check the EPO's delivery rules. We generally advise clients to enter key dates into the time limit management system as soon as they receive any EPO notification, and to set at least two rounds of reminders.

How should opposition and invalidation proceedings be coordinated with domestic procedures?

During the opposition period of a European patent, the same patent may also be involved in parallel proceedings in China and the United States. For example, inter partes review (IPR) or post-grant review (PGR) before the United States Patent and Trademark Office (USPTO), and within the European Union, invalidity actions before the Unified Patent Court (UPC). Evidence from these proceedings can be used across them, but the timelines are not coordinated. In practice, if European opposition and UPC invalidity proceedings are conducted simultaneously, it is necessary to coordinate the approach to claim amendments to avoid amending in one proceeding but not the other, which could lead to estoppel issues. For matters involving the interface between U.S. and EU proceedings, you may refer to U.S. and EU intellectual property legal services.

If the European patent is still in force in various countries, the outcome of the opposition only affects the patent text at the EPO level. The status of domestic rights after validation in each country still depends on local procedures. For example, Germany and France have their own invalidation proceedings, and the UK has a separate route after Brexit. For the procedural details in these countries, please refer to the intellectual property legal services of other countries.

What to do in the first 30 days after receiving a notice of objection?

First, confirm the delivery date and response deadline, and lock down the dates. Second, go through the opposition brief and all cited documents to determine which arguments the other side is mainly focusing on. Third, assess whether an extension is needed, and file for one as early as possible if so. Fourth, decide on the direction for amending the claims and prepare a draft response. Fifth, if a major product line is involved, simultaneously assess the appeal budget and timeline. Of these five steps, the first two can usually be completed within a week, while the third and fourth require coordination with the technical team, so don't put them off until the last month.

One more piece of practical experience: in opposition proceedings, the parties often enter a "further submissions" stage after the response, and the Opposition Division may issue multiple notifications. Each notification has a deadline, and missing one carries consequences just the same. Many clients, encountering this for the first time, fixate only on the initial three-month period and then let their guard down for the subsequent rounds of notifications, which is very risky.

Costs and business judgment—don't just look at the procedures.

The opposition procedure itself involves official fees, and an appeal incurs additional appeal fees. Add to that attorney fees, translation costs, and expert fees, and a complete European opposition through to appeal typically falls within a considerable cost range. The specific amount depends on the technical field and the complexity of the amendments. We generally recommend that clients conduct a "patent value vs. procedural cost" assessment before initiating a response. If the patent is defensive in nature and the product is no longer being sold, fighting it out may not be worthwhile; if the patent blocks a competitor's key product, then it is worth the investment. For trademark and patent arrangements involving other countries or regions, we have compiled them inIntellectual property legal services in other countries.

Procedural wins and losses are not the same as commercial ones. The Opposition Division upholding a patent does not mean the market will be easy; the Opposition Division revoking a patent does not mean the business will stop. Translating legal outcomes into business language is what decision-makers truly need.

The foreign-related intellectual property team at Guangdong Zhiming Law Firm has long handled European patent opposition, appeal, and related proceedings across various countries. To assess specific deadlines and response strategies, please call our hotline at 4008-363-555.

Disclaimer: The content of this article is provided for general legal information purposes only and does not constitute legal advice for any specific case. European patent opposition and appeal proceedings involve strict time limits and case-specific differences. For specific actions, please consider the facts of your case and consult a professional attorney. Our firm assumes no legal liability for consequences arising from actions taken or not taken based on the content of this article.