We would like to advocate for the description of PuO 2 as featuring a 5f 4 plutonium ion, consistent with n open = 4, because the system's valence electronic states of the ion's 5 I 4 level parentage and the system's magnetism are compatible only with this description. Undeniably, however, there is pronounced LM donation present in PuO 2 , as evidenced by the present analysis of first-principles quantum theoretical calculations and spectroscopic data. The Pu M 5 -edge and M 3 -edge HR-XANES and Pu M 5 -edge VB-RIXS results strongly support the theoretical calculations that Pu has a 5f 4 electron configuration with some participation of 5f electrons in covalent bonding such that n f > n open . The calculations point to n f being between 5.4 and 5.6 when the diffuse regions of the 5f shell are included in the population analysis. We showed here also the first examples of Pu M 5 -edge VB-RIXS and M 3 -edge HR-XANES of Pu materials.