At present, cosmological observations set the most stringent bound on the neutrino mass scale. Within the standard cosmological model (\(\Lambda\)CDM), the Planck collaboration reports \(\sum m_\nu < 0.12\,\text{eV}\) at 95% CL. This bound, taken at face value, excludes many neutrino mass models. However, unstable neutrinos, with lifetimes shorter than the age of the universe \(\tau_\nu \lesssim t_U\), represent a particle physics avenue to relax this constraint. Motivated by this fact, we present a taxonomy of neutrino decay modes, categorizing them in terms of particle content and final decay products. Taking into account the relevant phenomenological bounds, our analysis shows that 2-body decaying neutrinos into BSM particles are a promising option to relax cosmological neutrino mass bounds. We then build a simple extension of the type I seesaw scenario by adding one sterile state \(\nu_4\) and a Goldstone boson \(\phi\), in which \(\nu_i \to \nu_4 \, \phi\) decays can loosen the neutrino mass bounds up to \(\sum m_\nu \sim 1\,\text{eV}\), without spoiling the light neutrino mass generation mechanism. Remarkably, this is possible for a large range of the right-handed neutrino masses, from the electroweak up to the GUT scale. We successfully implement this idea in the context of minimal neutrino mass models based on a \(U(1)_{\mu-\tau}\) flavor symmetry, which are otherwise in tension with the current bound on \(\sum m_\nu\).