In this study, we compute the ground and valence-excited states with (specific) core electrons frozen. Hence, these states (and therefore, CCSD T , and the corresponding EOM-EE-CCSD Rval and Lval amplitudes) are computed in the configuration space spanning the reference and purely valence-excited determinants only. Therefore, in our frozen-core (fc) CVS-EOM-EE-CCSD model, the valence excitation space is uncoupled to the core-excitation space by construction. This is in contrast to the CVS model from Ref. 72, where the two spaces are decoupled by applying dedicated projectors. Nevertheless, the strategy described in this paper for computing X2PA spectra is general and applicable to both these variants of CVS-EOM-EE-CCSD. We call the Hamiltonian block defined by the reference and valence-excited determinants as Ĥval . The fc-CVS-EOM-EE-CCSD Hamiltonian, Ĥ, is then block diagonal and made up of Ĥval and Ĥcore blocks.