WARNING: Although the information which follows was correct at the time of original publication in the PCT Newsletter, some information may no longer be applicable; for example, amendments may have been made to the PCT Regulations and Administrative Instructions, as well as to PCT Forms, since the PCT Newsletter concerned was published; changes to certain fees and references to certain publications may no longer be valid. Wherever there is a reference to a PCT Rule, please check carefully whether the Rule in force at the date of publication of the advice has since been amended.
Q: I am going to file an international application electronically, in PDF format, containing a sequence listing. Since the International Searching Authority requires that sequence listings be submitted in text format for the purposes of international search, would it be possible to furnish the sequence listing after the filing of the international application?
A: It is recalled that according to PCT Rule 5.2(a), “where the international application contains disclosure of one or more nucleotide and/or amino acid sequences, the description shall contain a sequence listing complying with the standard provided for in the Administrative Instructions and presented as a separate part of the description in accordance with that standard”. The standard referred to is contained in Annex C of the PCT Administrative Instructions (“Standard for the Presentation of Nucleotide and Amino Acid Sequence Listings in International Patent Applications under the PCT”) and in WIPO Standard ST.25 (see: https://www.wipo.int/standards/en/pdf/03-25-01.pdf). A Standard‑compliant sequence listing will be referred to hereinafter as an Annex C/ST.25 sequence listing. An Annex C/ST.25 sequence listing is used for the prosecution of the application before all PCT Authorities (receiving Offices and International Searching Authorities (ISAs) and International Preliminary Examining Authorities (IPEAs)) in the international phase, as well as before the designated (or elected) Offices in the national phase (see PCT Rule 13ter.3).
Any sequence listing forming part of the international application must be filed at the same time as the rest of the international application, and be presented as a separate part of the description. If the sequence listing is submitted after the international filing date, it cannot normally be part of the international application, and will not be published with the international application. However, it might be possible to add it to the international application under certain circumstances (see penultimate paragraph, below). When submitting a sequence listing at the same time as the international application, you should clearly indicate that you are submitting it as part of the international application. In ePCT‑Filing you should use the “International search” tab. In the PCT‑SAFE software, you should check the box labeled “Description contains sequence listing” on the “Biology” page to create the sequence listing item on the “Contents” page.
When filing an international application electronically in PDF format, you are strongly advised to submit the sequence listing part of the description in text format, not only because the sequence listing must, in any case, be prepared in that format for the purposes of international search, but also to avoid having to pay extra fees; if the sequence listing part of the description is filed in PDF format (or on paper), the pages making up the sequence listing will be counted when determining the total number of pages/sheets of the international application and may be subject to the fee per sheet in excess of 30; this fee is not payable for sequence listings filed in text format.
Any sequence listing contained in an international application filed in electronic form must be in an electronic document format, and be filed by a means of transmittal that has been specified by the receiving Office for the purposes of filing of international applications in electronic form. Please be aware that when you file your international application using ePCT‑Filing or PCT‑SAFE, a basic check of the sequence listing file is made. Although the software does not fully verify that the sequence is valid, it does check the opening lines to ensure that certain required tags are included.
If the sequence listing does not meet the necessary requirements, or where nucleotide and/or amino acid sequences are disclosed in the application but no sequence listing has been filed, the ISA will invite you (using Form PCT/ISA/225) to furnish, within a fixed time limit, an Annex C/ST.25 sequence listing in electronic text form so that it can properly carry out the international search (PCT Rule 13ter.1(a)). In either situation, you would have to make a statement in your response that the sequence listing does not go beyond the disclosure in the international application as filed. You may also have to pay a late furnishing fee (PCT Rule 13ter.1(c)) to the ISA. If you fail to comply with the necessary requirements of the ISA, the international search may be restricted, that is, the examiner may not search claims directed to specific sequences (PCT Rule 13ter.1(d)). (Note that the requirements in relation to sequence listings for the purposes of international search also apply during international preliminary examination (PCT Rule 13ter.2).)
Where a sequence listing filed in text format for the purposes of international search does not form part of the international application and was sent direct to the ISA, the ISA will transmit a copy to the IB, and the IB will publish the sequence listing on PATENTSCOPE at the time of publication of the international application with an indication that it did not form part of the application.
Where the sequence listing contains any free text, that free text must be repeated in the main part of the description (see PCT Rule 5.2 and Annex C, paragraph 36).
Please see Annex C for detailed information about the Standard for the presentation of sequence listings. Please be advised that dedicated software is available free of charge for the preparation of sequence listings in electronic format, for example:
(1) “PatentIn” from the website of the United States Patent and Trademark Office at:
and also from the website of the Japan Patent Office at:
(2) BiSSAP from the website of the European Patent Office; for further details, see:
Note that if you fail to include the sequence listing as part of the application, it might be possible, under certain circumstances, for a later‑filed sequence listing to become part of the international application in the following situations:
- inclusion by incorporation by reference under PCT Rule 20.6, provided that the necessary conditions are met (see the “Practical Advice” in PCT Newsletter No. 12/2014). You should, however, be aware that PCT Rule 20.6 is not compatible with the national law of some receiving Offices and designated Offices, with the result that such Offices may not accept sequence listings which have been incorporated by reference (see the “Practical Advice” in PCT Newsletter No. 07‑08/2015);
- if a sequence listing cannot be incorporated by reference, it can be submitted to the RO within 2 months of the international filing date to complete the international application (PCT Rule 20.5(a)(i)). In this situation the date of submission of the sequence listing will become the international filing date;
- if you file a demand for international preliminary examination, a sequence listing may be filed as an amendment of the description under PCT Article 34, provided that it does not go beyond the disclosure in the international application as filed (PCT Rule 13ter.1(e)).
Further information on the filing of sequence listings is available in the PCT Applicant’s Guide, International Phase, paragraphs 5.099 to 5.104 and 7.005 to 7.012 at:
and in the Administrative Instructions, Annex C, at:
Date retrieved: 17 May 2021