Timber-concrete composites (TCC) represent one solution for slabs in residential and office buildings, combining the low carbon footprint and sustainability of responsibly sourced timber with the higher stiffness, thermal mass, fire resistance and acoustic insulation of concrete. However, a non-negligible disadvantage is that the current practice of TCC slab systems is often limited to load-carrying as single-span beams. This paper presents an analytical model based on the component method for determining the joint stiffness of continuous TCC slabs in the range with negative bending moments. The study involves the development of load-displacement curves for individual force-transmitting components and their assembly into a component model. Validation through finite element calculations demonstrates the accurate representation of the moment-rotation relation in continuous TCC systems. Considering the substantial influence of input value variability on the joint stiffness, a probabilistic analysis of the model parameters was conducted. The results from the probabilistic investigations enable initial statements about the joint stiffness of continuous timber-concrete composite slabs in ranges with negative bending moments.