Co-fired integrated circuit devices and methods for fabricating and integrating such on a workpiece are disclosed herein. An exemplary method includes forming a first passive device and a second passive device over a carrier substrate. The first passive device and the second passive device each include at least one material layer that includes a co-fired ceramic material. The carrier substrate is removed after performing a co-firing process to cause chemical changes in the co-fired ceramic material. The first passive device may include a conductive loop disposed between a first magnetic layer and a second magnetic layer. The first magnetic layer, the second magnetic layer, or both includes a co-fired ceramic magnetic material. The second passive device may include a first conductive layer and a second conductive layer separated by a dielectric layer. The first conductive layer, the second conductive layer, or both includes a co-fired ceramic conductive material.