For the purpose of the procedure before the EPO as designated/elected Office the applicant may always file (voluntary) amendments within the 31-month time limit, and if he subsequently changes his mind he may file (further) amendments until expiry of the time limit set in the combined communication under Rules 161 and 162 EPC (Rule 161 EPC/Rule 162 EPC communication). As set out below, and if the EPO acted as International Searching Authority, the applicant may also be required to file (mandatory) amendments to and/or comments on the application within the time limit set in the Rule 161 EPC/Rule 162 EPC communication (see point 498499). Whether or not a response is mandatory is clearly stated in the communication, its wording thus differing depending on the case (EPO Forms 1226AA and 1226BB).

After expiry of the six-month time limit further possibilities for amending the application are limited. If a supplementary European search is carried out, the applicant always has one further opportunity to submit amendments upon receipt of the report (see point 493494). Amendments made thereafter require the consent of the examining division. By way of exception, in cases where the supplementary European search is dispensed with (EPO was (S)ISA) and, after expiry of the period according to Rule 161(1) EPC, a further search is carried out in the European phase according to Rule 164(2)(a) EPC (see points 654655-see points 655656), the applicant may also submit amendments in response to the communication of the results of that search in accordance with Rule 164(2)(b) EPC and without requiring the consent of the examining division.

Amendments may under no circumstances go beyond the disclosure in the international application as filed. 

Whenever amendments are filed, the applicant must identify them and indicate their basis in the application as filed. If he fails to do so, the examining division may issue a communication requesting correction of the omission within a non-extendable time limit of one month. If the deficiency is not remedied in due time, the application will be deemed withdrawn under Article 94(4) EPC. The loss of rights can be remedied with further processing.