While non-heme iron halogenases are known to carry out C-H chlorination and bromination, C-H fluorination activity has never been observed in these enzymes. We showed through a combination of DFT and WFT that there are significant differences between the smaller fluoride and the larger chloride/bromide intermediates in terms of their structural and energetic preferences. While HAT reactions were found to be comparable for all three halides, we observed crucial differences in radical rebound reaction barriers for fluoride relative to chloride/bromide intermediates. The larger halide-rebound reaction barriers for fluoride intermediates in comparison to chloride/bromide intermediates could explain the challenges of C-H fluorination relative to C-H chlorination and bromination.