How to Amend PCT Application

Does Your PCT Application Require Any Amendments?

Before delving into the complexities of filing amendments to a PCT application, the initial question to consider is whether an amendment is even necessary. For example, if you have a co-pending US application with claims that received a first action allowance, then PCT amendments might be unnecessary. Here are some helpful goals to consider in determining whether you should amend a PCT application.

Amend a PCT application to streamline national stage applications

Filing a single amendment in your PCT application is an efficient way to avoid duplicate filings in each subsequent national phase application. For example, if minor cleanup is required of the specification or drawings, then a PCT amendment would be advisable.

Amend a PCT application to obtain a favorable opinion for PPH

Prosecuting national stage applications can be a very long and expensive process, so any solution to reduce pendency and costs should always be considered. If the Patent Prosecution Highway is available (both your PCT search authority and the desired national stage country must be PPH members), then it may be worthwhile to amend the claims and to request a favorable opinion on the amended claims.

Amending More Than Claims

The need to amend more than just the claims will also dictate the type of PCT amendment to file.

What are the stages of a PCT application?

It may help to think of a pending PCT application as having two stages of review. All PCT applications pass through a first stage called Chapter I (“chapter one”). The second stage called Chapter II (“chapter two”) is an optional phase that is entered only if an applicant files a Chapter II Demand which carries a government fee. These stages are relevant for determining the type of PCT amendment to be filed as well as the associated deadline.

Ultimately, the type of PCT amendment that makes the most sense for your PCT application will depend upon the goals you wish to achieve with the PCT application.

Chapter I: Article 19 Amendment

In the Chapter I phase that all PCT applications go through, an initial review of the claims will be performed by the chosen patent office. That initial review known as an international search will result in a summary document called an International Search Report (ISR) and Written Opinion (WO). The ISR+WO will contain preliminary and non-binding findings on the allowability of the claims.

During this Chapter I phase, an applicant may file an Article 19 Amendment to revise only the claims. Amendments to the specification or drawings are not allowed in Article 19 amendment. No government fees are required for filing an Article 19 Amendment.

The deadline for filing an Article 19 Amendment is the later of 16 months from the priority date or 2 months from the ISR.  If filed early enough, the publication of your PCT application may contain the Article 19 amended claims, which can avoid the need to file multiple preliminary amendments in each national stage application.

Chapter II: Article 34 Amendment

If the first opinion in Chapter I was unfavorable, it may be worthwhile to seek a second opinion on amended claims. The only way to request such a second PCT opinion, called the International Preliminary Examination Report (IPER), is to file a Chapter II demand. Such a second opinion may also be referred to as

When a Chapter II demand is filed, the applicant has the right to file an Article 34 amendment which can revise not only the claims, but the specification and drawings as well.

The deadline for filing a Chapter II demand is 22 months from the priority date. As a practical matter, it would be prudent to file an Article 34 amendment concurrently with the Chapter II demand so that such amendments would be timely considered before the second opinion is issued. Technically, an Article 34 amendment may be filed anytime prior to the issuance of the IPER. However, we would not recommend filing an Article 34 demand significantly later than the Chapter II demand since such a late filing might not be considered prior to the issuance of the second opinion.

Need to amend a PCT application?

Contact US patent attorney Vic Lin by email at or call (949) 223-9623 to see how we can develop and execute an international patent strategy for you.

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