We study two reactions that are crucial for C-H halogenation for fluoride, chloride, and bromide intermediates: the rate-determining HAT reaction and the competing rebound hydroxylation or halogenation reactions. We investigate HAT and rebound reactions to understand if differences across three halides for these reactions could explain why C-H chlorination or bromination are observed but fluorination is not observed. We study rebound of the substrate radical to both We model the HAT reactions using a bidentate succinate isomer with axial oxo and equatorial halide, which is the most stable isomer for the chloride Fe(IV)=O intermediate. While this is not the most stable isomer for fluoride or bromide intermediates, it is used for HAT reactions across all halides to enable consistent comparisons across halides and also because all bidentate succinate isomers are comparable in energy for the three halides (Figure ). We find that the HAT reactions are accompanied by a significant reaction barrier (ca. 25 kcal/mol) for all halides suggesting that the nature of HAT is largely independent of the halide in the active site (Figure ).