Article 4
Date of effect

1.A European patent with unitary effect shall take effect in the participating Member States on the date of publication by the EPO of the mention of the grant of the European patent in the European Patent Bulletin. 

2.The participating Member States shall take the necessary measures to ensure that, where the unitary effect of a European patent has been registered and extends to their territory, that European patent is deemed not to have taken effect as a national patent in their territory on the date of publication of the mention of the grant in the European Patent Bulletin.