Informal comments allow an applicant to place a rebuttal to the ISA Written Opinion on the international application record without requesting Chapter II international preliminary examination. They do not amend the application and do not require the ISA to reconsider its opinion.
Informal comments are most coherent where the applicant wants to rebut reasoning but does not need the international claim text changed through this mechanism. If claim amendments are central to the strategy, Article 19 or Chapter II should be assessed instead of treating comments as a substitute.
Organize the response by the Written Opinion’s actual novelty, inventive-step or other findings. Identify the claim or claim group, the cited passage relied on by the examiner, the applicant’s technical distinction, and why the cited material does not establish the stated conclusion. A compact issue-by-issue structure is more useful than a broad advocacy narrative.
Designated Offices are not bound by informal comments. The comments should therefore be written so they can inform later prosecution without assuming that every national office will use the same legal test or reach the same conclusion. Avoid concessions that are unnecessary to explain the applicant’s international-phase position.
Confirm the applicable WIPO timing guidance before filing and keep a dated copy of what was submitted. The practical value of comments is tied to whether they become available to designated Offices in time to support national-phase review. Filing late may reduce that value even where the document can still be retained in the international file.
Informal comments are designed for applicants who want to rebut findings in the ISA Written Opinion without requesting international preliminary examination. Their value is primarily communicative: they can accompany the international record made available to designated Offices, but they do not change the claims and they are not a formal request for reconsideration by the ISA.
| Where filed | International Bureau | Competent IPEA |
| Formal reconsideration | No | Yes, through international preliminary examination |
| Amend claims/description/drawings | No | Yes, under Article 34 |
| Main value | Place rebuttal on record | Obtain further international examination |
| National-phase role | Background for designated Offices | IPRP Chapter II plus response record |
The mechanism is distinct from a formal Chapter II response. WIPO guidance describes informal comments as comments on the ISA Written Opinion sent to the International Bureau for availability to designated Offices.
If claim text needs to change, Article 19 or Article 34 is the relevant amendment route. Informal comments should not be drafted as though they alter the application.
The ISA is not required to revisit its Written Opinion merely because informal comments are filed. Applicants seeking formal international preliminary examination should consider Chapter II.
WIPO practical guidance recommends filing informal comments before 28 months from the priority date so they can be available to designated Offices on national-phase entry. The practical objective is to place the applicant position into the international record early enough to travel with the file.
Comments should identify the affected claims, the finding being disputed, the cited reference or reasoning, and the applicant response. This makes the document easier for later offices to use.
Informal comments are not a binding determination of patentability and do not guarantee that a national Office will accept the applicant position.
Where the same search-stage reasoning is likely to be reviewed by several designated Offices, a disciplined rebuttal can reduce the need to recreate the same factual explanation from scratch.
If the applicant believes the claims already distinguish over the cited art and does not need international preliminary examination, comments may provide a lower-complexity way to state that position.
If the applicant wants an IPEA to consider arguments and amendments before national phase, Chapter II and Article 34 provide the formal route.
Each designated Office applies its own law and procedure. Informal comments should therefore be treated as a reusable analytical record, not as a universal national-phase response.
PCT rules, forms, fees, competent Authorities and national-phase requirements can change. Verify the current WIPO materials and the requirements of the relevant ISA, IPEA and designated Offices before acting on a specific application.
PCT response strategy is strongest when the Written Opinion, cited prior art, amendment basis, target markets and expected national-phase prosecution are considered together.
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