Rating trigger ATE (Additional Termination Event) is a counterparty risk mitigant that allows banks to terminate and close out bilateral derivative contracts if the credit rating of the counterparty falls below the trigger level. Since credit default is often preceded by rating downgrades, ATE clause effectively reduces the counterparty credit risk by early termination of exposure. However, there is still the risk that counterparty may default without going through severe downgrade. This article presents a practical model for valuating CVA in the presence of ATE.