Flow chart summarising our selection criteria used to isolate candidates from the eFEDS AGN sample. Each box contains a selection method with the cuts applied and the number of sources obtained in the bottom right corner of each box. In brackets, we indicate the number of sources for z less than one (0.5 < z < 1) which we apply later on for SDSS spectra analysis. By reliable spectroscopic or photometric redshift, we only consider redshift grade 4 or 5 – see Salvato et al. (2022). F_opt refers to flux in the optical r-band. The box highlighted in red is sample A obtained after applying the colour selections in the top right of Fig. 1. The box highlighted in blue is the N_H > 10^21.5 cm⁻² and selection or sample B in Fig. 2.