The answer depends on the state where you are certified. In general, the proof of employment must be in the form of either: a pay stub, payroll printout, or notarized attestation form. Usually, the notarized attestation form must be completed and notarized by the facility where you worked and must include the following: your name, social security number, the dates you worked and, the name and title of the individual verifying this information such as your RN supervisor. Furthermore, some states require a fee for late renewal and it is best to contact the registry and ask what their requirements are. You can find contact information for all CNA registries here or by using the menu available on most pages of this website.