  Whenever a system possesses a conserved charge, the density matrix splits
into eigenspaces associated to the each symmetry sector and we can access the
entanglement entropy in a given subspace, known as symmetry resolved
entanglement (SRE). Here, we first evaluate the SRE for massless Dirac fermions
in a system at finite temperature and size, i.e. on a torus. Then we add a
massive term to the Dirac action and we treat it as a perturbation of the
massless theory. The charge-dependent entropies turn out to be equally
distributed among all the symmetry sectors at leading order. However, we find
subleading corrections which depend both on the mass and on the boundary
conditions along the torus. We also study the resolution of the fermionic
negativity in terms of the charge imbalance between two subsystems. We show
that also for this quantity, the presence of the mass alters the equipartition
among the different imbalance sectors at subleading order.
