In this presentation, we will provide an overview of the CRTM with a focus on the improvements that have been or will soon be implemented in CRTM. The model includes a multiple transmittance algorithm framework, which allows different transmittance algorithms to coexist, such as the OPTRAN algorithm (Optical Path TRANsmittance), and the ODPS algorithm (Optical Depth in Pressure Space). In addition, special algorithms are implemented to take into account Zeeman-splitting effect for the SSMIS and AMSU-A sensors, CO2 cell pressure leaking effect for the Stratospheric Sounding Unit (SSU), and corrections of the Non Local Thermodynamic Equilibrium (NLTE) effect for IR sensors. In regards to surface optics updates we will describe the implementation of a physical microwave land surface emissivity model and a new microwave sea surface emissivity model (FASTEM5). We are evaluating several microwave and infrared land surface emissivity databases in CRTM. Additionally, we will describe the integration of the Successive Order of Interaction (SOI) radiative transfer model.