The error distribution curve for the corrected SS-FNO and FNO-IP-EOM-CCSD* method with respect to untruncated canonical results for the Cheng test set has been plotted in Figure . The corresponding statistical parameters for the FNO-IP-EOM-CCSD* method are presented in Table . The error in the corrected FNO-IP-EOM-CCSD* improves on going from the excited state threshold of 10 -4 to 10 -4.5 . However, the errors are still higher than the corrected SS-FNO version at both thresholds. Upon a closer examination of the results, it becomes evident that the error in the uncorrected FNO-IP-EOM-CCSD* method is lower than the corresponding uncorrected SS-FNO-IP-EOM-CCSD* method at a threshold of 10 -4 and 10 -4.5 . For example, the MAD in the uncorrected FNO-IP-EOM-CCSD* method at a 10 -4 threshold is 0.334 eV, which is lower than the corresponding SS-FNO value of 0.501 eV. It is the inclusion of perturbative correction that significantly improves the results for core-IP in the SS-FNO-IP-EOM-CCSD* method, resulting in a reduced MAD of 0.073 eV.