The paper re-examines the ΔCCSD (state-specific coupled-cluster) method, which uses non-Aufbau determinants to target excited states, particularly doubly excited states. The authors compare the effectiveness of ΔCCSD with EOM-CCSD (equation-of-motion coupled-cluster) for various types of excited states, including doublet–doublet transitions and singlet and triplet singly excited states of closed-shell systems. They use a benchmark set of 276 excited states from the quest database to evaluate the accuracy of both methods. The results show that ΔCCSD underperforms EOM-CCSD for most excited states, except for doublet–doublet transitions where the differences in mean absolute errors (MAEs) are less pronounced. The discrepancy is attributed to the presence of multiconfigurational characters in the latter set of excited states, which are more challenging for ΔCCSD. The paper also discusses the benefits of using state-specific optimized orbitals and highlights the limitations of ΔCCSD for certain types of excited states.The paper re-examines the ΔCCSD (state-specific coupled-cluster) method, which uses non-Aufbau determinants to target excited states, particularly doubly excited states. The authors compare the effectiveness of ΔCCSD with EOM-CCSD (equation-of-motion coupled-cluster) for various types of excited states, including doublet–doublet transitions and singlet and triplet singly excited states of closed-shell systems. They use a benchmark set of 276 excited states from the quest database to evaluate the accuracy of both methods. The results show that ΔCCSD underperforms EOM-CCSD for most excited states, except for doublet–doublet transitions where the differences in mean absolute errors (MAEs) are less pronounced. The discrepancy is attributed to the presence of multiconfigurational characters in the latter set of excited states, which are more challenging for ΔCCSD. The paper also discusses the benefits of using state-specific optimized orbitals and highlights the limitations of ΔCCSD for certain types of excited states.