A capacitor strap that is applied to a security tag coil or antenna to form and properly tune an EAS or an RFID security tag. The capacitor strap is a thin film capacitor formed of two metal foils in between which is a dielectric material having ends that are electrically coupled to different points of a security tag coil or antenna. The capacitor strap may include an RFID integrated circuit, either in series or in parallel with the capacitor, which is then applied to security tag coil at a particular location to tune the tag to a predetermined frequency.