We study a fully nonlinear free transmission problem in the presence of general degeneracy terms. Under minimal conditions on the degeneracy of the model, we establish the existence of viscosity solutions for the associated Dirichlet problem. Once the existence of solutions has been established, we focus on their regularity estimates. By imposing a Dini-continuity condition on the degeneracy laws involved in the model, we prove that viscosity solutions are locally differentiable.