Denials from the Comprehensive Error Rate Testing (CERT) project can confuse pro-viders, but don't forget you can appeal. Resource: If your HHH MAC is National Government Services, you can use its new CERT Denial Reason Finder self-service tool to locate the denial reason definition, understand why the claim was denied, view CERT reviewer comments, and learn how to correct the error, NGS says in a message to providers. You can find the tool at www.ngsmedicare.com/wps/portal/ngsmedicare/certstatus. You just enter the CERT claim identification (CID) number in the tool's search form field then select "Submit." You can appeal the decision online at the MAC's NGSConnex.com online portal.