PCT Newsletter

January 2026 | No. 01/2026

Practical Advice

Essential information to be included in an international application if a last-minute filing cannot be avoided

Q.: Our client has instructed our patent firm only this morning, the last day of the priority period, to file a PCT application. We have the description, claims and drawings, which will be the same as the priority application. We still need to contact the client to double-check whether we have all the information desired to be included in the application but we are concerned about missing the priority period. What information must we submit with the international application before the priority period expires?  
A.: Before the priority period expires, you need to submit everything that is necessary to obtain an international filing date and any information that you cannot add or correct subsequently without affecting the international filing date. 
The requirements for obtaining an international filing date are listed in PCT Article 11(1). As far as the bibliographic data is concerned, in addition to the applicant’s name, it is essential to indicate a country of nationality or residence which is a PCT Contracting State. You need this information to show that the applicant does not obviously lack, for reasons of residence or nationality, the right to file an international application with the receiving Office (RO). Residence or nationality depends on national law of the relevant Contracting State and is determined by the RO. PCT Article 11(1)(i) and (ii) further require that the application be filed with a competent RO and be in a prescribed language. However, if these conditions are not fulfilled, PCT Rule 19.4 requires the RO to transmit the application to the International Bureau as a receiving Office (RO/IB), which is a competent RO for all Contracting States and accepts any language for the purpose of according an international filing date. 
You must include the name, address and nationality of the applicant in the request form filed in the application. However, provided you can demonstrate that the applicant has the right to file the international application with the receiving Office for reasons of residency or nationality, if there are inaccuracies in the address, you may be able to request a change to be recorded under PCT Rule 92bis after filing without affecting the international filing date that has been accorded.  
To obtain an international filing date, the application must also include an indication that it is intended as a PCT application and the designation of at least one PCT Contracting State. These indications are generated by the electronic filing systems accepted by the various ROs for PCT applications, noting that PCT Rule 4.9 states that the filing of a PCT Request constitutes the designation of all Contracting States that are bound by the PCT on the international filing date. 
The Request must be signed, and where it is signed by the agent, in general a power of attorney signed by the applicant must be furnished (PCT Rules 4.1(d), 4.15, 26.2bis(a), 51bis.1(a)(vi) and 90). However, most ROs have waived the requirement that a power be furnished and therefore will not invite you to furnish one if it is missing (for details about each RO, consult the PCT Applicant’s Guide, Annex C and the webpage on Waivers of powers of attorney requirement). Moreover, you can add a missing signature and correct a defect relating to the signature under Article 14(1)(a)(i) and PCT Rule 26 after filing, without affecting the international filing date. You should therefore not continue trying to obtain the applicant’s (or agent’s) signature at the risk of missing the priority period. It is important, however, that you have the power of attorney in your own file as soon as possible in case you need to withdraw the application later (in which case the signature of all applicants is always required—PCT Rule 90bis.5). Also, in the national phase, designated Offices may ask you to submit any power which had not been submitted in the international phase. 
You may also want to ask the client for other details at this stage, even it is possible to add or correct them within specific time limits and maintain the international filing date accorded to the application. For example, priority claims (PCT Rules 4.10 and 26bis), declarations (PCT Rules 4.17 and 26ter) and any indications relating to a designation as continuation or continuation-in-part (PCT Rules 4.11 and 26quater) may be added or corrected without affecting the international filing date. It is also possible to submit an abstract for the international application after the international filing date.  
Furthermore, fees may be paid within one month from the international filing date (PCT Rules 14.1(c), 15.3 and 16.1(f)), and may be even paid within an additional month subject to the payment of a  late payment fee (refer to PCT Rule 16bis). As the RO will not transmit the search copy before the search fee has been paid, it is recommended to pay as soon as possible as this could affect when you receive the international search report and written opinion. Any required translation for the international search and/or publication should also be furnished as soon as possible; for details, please refer to PCT Rule 12.3 and 12.4.
Further information can be found in the Practical Advice in the following issues of the PCT Newsletter:

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