A cartridge is provided for an electrically heatable aerosol-generating system, the cartridge including: an aerosol-forming substrate including a liquid held in a capillary material; and a susceptor element including first and second fluid-permeable portions, the first fluid-permeable portion being disposed on a first side of the capillary material, and the second fluid-permeable portion being disposed on a second side of the capillary material opposite to the first side such that the capillary material is located in between the first and the second fluid-permeable portions of the susceptor element, the susceptor element being electrically isolated from other electrically conductive components. A heater assembly for an electrically heatable aerosol-generating system, and an electrically heatable aerosol-generating system, are also provided.