Rare and BSM Higgs Searches

Recent searches for rare and BSM Higgs boson decays with the ATLAS and CMS experiments on data collected at $\sqrt{s}$ = 13 TeV between 2016 and 2018 are presented. These represent previously inaccessible probes of the Higgs properties, enabled by advanced analysis and machine learning methods, as well as the large amount of data collected during the Run2 of the LHC. Topics covered include standard model Higgs decays with a branching fraction magnitude equal to that into charm quarks or lower along with searches for decays into yet unobserved particles or decays of Higgs-like and extended Higgs sector particles.