1. Month, day, and year that a professional service is rendered or a supply item is given to a patient by a provider. This date is entered on the patient’s encounter form and charted in the patient’s medical record along with documentation by the provider detailing the services and/or supplies provided, chief complaint, examination, and when the patient should return for an appointment. 2. When an insurance claim is manually submitted, the date of service is inserted in Block 24A of the CMS-1500 insurance claim form. This indicates the date on which health care services were provided to the insured. More than one date of service may be listed on a claim. Also called service date .