The Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) is a stand and landscape-level modeling framework to simulate forest carbon dynamics. It is the central model of Canada's National Forest Carbon Monitoring, Accounting and Reporting System used for national and international reporting of the greenhouse gas balance of Canada's managed forest. Recalibration of soil parameters was undertaken to reflect recent changes to the CBM-CFS3 that influence soil carbon stock and flux estimation. A database of forest soil carbon was analyzed to distinguish groups of soil taxonomic units with significantly different carbon stocks (soil carbon groups) and interactions with tree species were also explored. Using a separate dataset (coupled tree and soil carbon data) decay rates were calibrated for the forest floor and mineral soil for each soil carbon group. The Soil Landscapes of Canada was used to apply the soil carbon group stratification and their associated parameters spatially across Canada. Regional estimates of soil carbon stocks predicted by CBM-CFS3 using the calibrated parameters were compared with independent estimated from the Canadian Soil Organic Carbon Database (CSOCD). Results from the soil carbon group stratification, decay rate parameterization, and validation are presented.