CECL is the new credit loss model that will replace the existing incurred loss model. Under CECL, banks will have to predict future credit losses from the day a loan is issued by adjusting historical losses for reasonable and supportable forecasts. To prepare, banks need to improve data collection, particularly loan-level data and transaction details over time, as well as gather data on loan losses and durations under different economic conditions. Banks also need to identify relevant economic metrics, develop forecasts for those metrics, and translate the forecasts into expected loss estimates using correlations identified in historical data. Proper implementation will require changes to processes, controls, reporting, and capital planning.