We review the analysis of the 5 sigma discovery contours for the charged MSSM Higgs boson at the CMS experiment with 30 fb^-1 for the two cases M_H+ < m_t and M_H+ > m_t. Latest results for the CMS experimental sensitivities based on full simulation studies are combined with state-of-the-art theoretical predictions of MSSM Higgs-boson production and decay properties. Special focus is put on the SUSY parameter dependence of the 5 sigma contours. The variation of mu can shift the prospective discovery reach in tan_beta by up to Delta tan_beta = 40. We furthermore discuss various theory uncertainties on the signal cross section and branching ratio calculations. In order to arrive at a reliable interpretation of a signal of the charged MSSM Higgs boson at the LHC a strong reduction in the relevant theory uncertainties will be necessary.