The EPO has so many publication dates for each patent: A1, A2, A3, A4. . . B1, B2, etc.

Which should I use as publication date?

  • 1
    Each of those Kind Codes represents a different type of document that serves a different purpose. They are all publication dates. Are you asking specifically for the Priority Date?
    – Kimmy W.
    Commented Jul 24, 2015 at 3:29

2 Answers 2


You should use the date of the A1 or A2 publication for the earliest publication date of the subject-matter (of the application).

(If you want to know about the granted patent please clarify.)

A1 is a publication of the application with search report (SR).

A2 is the publication without SR. There will be always only one or the other.

An A3 is published later in case of an A2 as soon as the search has been carried out. See here for more details on the so called kind codes: https://register.epo.org/helphttps://register.epo.org/help?lng=en&topic=kindcodes

18 months after the filing date, an application is published by the EPO according to Article 93(1)(a) EPC:

"The European Patent Office shall publish the European patent application as soon as possible 

(a) after the expiry of a period of eighteen months from the date of filing or, if priority has been claimed, from the date of priority"

, if not requested earlier.

  • I think it's implicit already, but you may consider explicitly mentioning that the date of the A1/A2 is what should be used for the publication date (and not the A3). Such an explicit answer to the "Which should I use as publication date" question might help a user with less background knowledge.
    – Maca
    Commented Feb 29, 2016 at 10:26

Always the first one. The follow-ups are for some administrative and/or legal backlogs.

  • First one as in A1? (and not A2)?
    – Patent
    Commented Jun 28, 2015 at 10:26
  • 1
    By first one I meant the date of first publication. e.g. the first publication no. with suffix A2 signifies one or more relevant document or action is not completed. On completion of that requirement republication takes place with suffix A3. For all practical and legal purposes the publication date is the date of publication with suffix A2 as that is the date the patent applicattion was put in public domain. Commented Jul 24, 2015 at 3:03

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