The embedding-based method perfectly complements the idea of reducing the Hilbert space based on the localized nature of core orbitals and their influence from neighboring atoms and paves the way to a scalable approach for high level methods. This embeddingbased method can be extended for core-excitation with the EE-EOM-CC method. This approach would also be useful for the scaling of other wave function based methods like ADC(n) for simulation of core-spectroscopy of large systems. Another direction to pursue is the simulation of core-hole ionization of strongly-correlated materials using multireference methods.