PCT Newsletter

February 2026 | No. 02/2026

Practical Advice

Submitting amendments under PCT Article 34 after filing a demand for international preliminary examination 

Q: I would like to file a demand for international preliminary examination together with amendments to the description and drawings. The time limit to file the demand is about to expire. Is it possible to obtain more time to submit the amendments if they are not ready?
A: International preliminary examination is an optional procedure that provides the only possibility during the international phase for an applicant to amend the description, claims and drawings of an international application. This possibility is provided by PCT Article 34, which also provides the right for an applicant to communicate orally and in writing with the International Preliminary Examining Authority (IPEA). The examiner at the IPEA will therefore be able to consider amendments and arguments submitted by the applicant, and this may give the applicant further opportunities to make amendments, as provided by PCT Rules 66.3 and 66.4, before the IPEA establishes the international preliminary examination report. By contrast, without filing a demand for international preliminary examination, an applicant has only one opportunity to amend the claims of an international application before the International Bureau under PCT Article 19, where the amended claims are published but not considered during the international phase. International preliminary examination is often referred to as the procedure under Chapter II, as it is governed by Chapter II of the PCT. 
The time limit to file a demand for international preliminary examination is either (i) three months from the date of the transmittal of the international search report (ISR) and the written opinion by the International Searching Authority (ISA) or (ii) 22 months from the priority date, whichever expires later (PCT Rule 54bis.1(a)).  
Generally, the IPEA may start international preliminary examination as soon as it is in possession of the demand, the fees due, the ISR and the written opinion of the ISA, provided that any translation required under PCT Rule 55.2 has been furnished. It is therefore advisable to file the demand and pay the applicable fees as soon as possible after you receive the results of the international search since the earlier the examination starts, the more time you will have to communicate with the examiner before the IPEA must establish its report. It is generally recommended to submit amendments and any arguments at the same time as filing the demand, noting that the IPEA need not take into account any amendments or arguments which it receives after it has begun to draw up its own written opinion or the report under PCT Rule 66.4bis).    
If your amendments are not ready when the time limit under PCT Rule 54bis.1(a) to file a demand is about to expire, and you wish the international preliminary examination to start on the basis of the amendments, it is important to ensure that at least the demand is filed within the time limit[1].  You should indicate in the demand that you wish the international preliminary examination to start on the basis of the description, claims or drawings as amended under PCT Article 34 (Box No. IV of Form PCT/IPEA/401). If no such amendments have in fact been submitted, the IPEA will invite you to submit them within a time limit fixed in the invitation (PCT Rule 60.1(g)) (using Form PCT/IPEA/431). The IPEA will not start examination before it has received the amendments, or before the time limit fixed in the invitation has expired (PCT Rules 60.1(g) and  69.1(e)). Please note that as this will delay the start of the examination, you may have less time to communicate with the examiner, noting that the IPEA must still establish the report within the time limit of PCT Rule 69.2, that is (where any required translation has been furnished together with the demand), 28 months from the priority date or 6 months from the start of the examination, whichever expires last. 
Further information can be found in the Practical Advice in the following issues of the PCT Newsletter:
  • 03/2005: Time limit for submitting a formal response to a written opinion of the ISA where a demand for international preliminary examination is being filed 
  • 06/2019: The timing of the start of the international preliminary examination (following the amendment to PCT Rule 69.1(a))  
[1] The demand may be submitted via ePCT to the International Bureau, which will transmit it to the competent IPEA in accordance with PCT Article 31(6)(a) and Rule 59.3. In this case, the demand will be considered to have been received by the competent IPEA on the date of receipt by the International Bureau.

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