The central industrial property office of a contracting state must apply the procedure for the grant of a national patent or another protective right provided for by the legislation of this state at the request of the applicant for or the proprietor of the European patent under the circumstances specified in Art. 135(1). If the request for conversion is not filed within the three-month period specified in Rule 155(1), the effect referred to in Art. 66 will lapse (i.e. the European application will cease to be equivalent to a regular national filing in the designated contracting states).[Art. 135; ]

The request for conversion is to be made to the EPO, except where the application is deemed withdrawn pursuant to Art. 77(3); in this case the request is filed with the central industrial property office with which the application was filed. That office shall, subject to the provisions of national security, transmit the request directly to the central industrial property offices of the contracting states specified therein, together with a copy of the file relating to the European patent application. If the central industrial property office with which the application was filed does not transmit the request before the expiry of twenty months from the filing date, or if claimed, from the priority date, then Art. 135(4) applies (i.e. the effect of Art. 66 lapses).[Art. 135(2); Rule 155(2); Rule 155(3); ]

If a request for conversion is filed with the EPO, it must specify the contracting states in which the application of national procedures is desired and be accompanied by a conversion fee. In the absence of the fee the applicant or proprietor is notified that the request will not be deemed to be filed until the fee is paid. The EPO transmits the request to the central industrial property offices of the specified contracting states accompanied by a copy of the files relating to the European application or patent.[Art. 135(3); Rule 155(2); ]