The Date of Service (DOS) refers to the specific day on which a healthcare service, treatment, or procedure was provided to a patient by a medical professional or facility. This date is crucial for insurance claims, billing, and reimbursement processes, as it determines coverage eligibility, claim filing deadlines, and benefits under a policy.

The Date of Service appears on medical bills, insurance claims, and Explanation of Benefits (EOB) statements. It helps insurance companies verify that the treatment was received while the patient’s policy was active. Claims submitted with incorrect or missing DOS may be denied or delayed. Different services, such as hospital stays or multi-day treatments, may have multiple dates of service, while one-time visits, like routine check-ups, have a single DOS.

Insurance providers often set time limits for submitting claims based on the DOS. Policyholders should review their claims and EOBs to ensure the DOS matches their medical records. Keeping track of these dates helps patients manage their healthcare expenses, dispute billing errors, and confirm insurance payments. Proper documentation of the DOS is essential for smooth claim processing and avoiding unexpected out-of-pocket costs.