Under the applicable national provisions of the Extension States, the extension fee must be paid within the periods prescribed by the EPC for the payment of designation fees (see III, 12.2, III, 12.10 and VII, 1.3). If the extension fee has not been paid within the applicable basic time limit (Art. 79(2), Rules 15(2), 25(2) and 107(1)(d)), a communication under Rule 85a(1) is not issued. However, the applicant may still validly pay the extension fee within a period of grace of two months after the expiry of the basic time limit provided that within this period a surcharge of 50% of the extension fee is also paid (Rule 85a(2)). As regards the ceiling of the surcharge, Art. 2, No. 3b and No. 3c, RFees applies mutatis mutandis. Rule 108(3) is not applicable to extension fees.

If the extension fee and where appropriate the surcharge are not paid within the specified periods, the request for extension is deemed withdrawn. No communication under Rule 69(1) is issued, nor is re-establishment of rights possible in respect of payment of the extension fee.