The healthcare system relies on various identifiers to manage records, process claims, and ensure proper treatment. Different numbers serve fundamentally different roles, ranging from government financial tracking to internal record-keeping. While all identifiers point to a single person, their scope, function, and required security vary significantly. Understanding the distinction between the Social Security Number (SSN), the former Health Insurance Claim Number (HICN), the current Medicare Beneficiary Identifier (MBI), and the internal Patient ID helps individuals protect their personal information.
Defining Governmental Identifiers: SSN, HICN, and MBI
The Social Security Number (SSN) is the longest-standing governmental identifier, created for tracking individual earnings and administering Social Security benefits. This nine-digit number acts as a universal identifier for taxation and financial purposes. Providers often request the SSN for identity verification or debt collection, making it the highest-risk identifier to share.
The Health Insurance Claim Number (HICN) was the previous identifier for Medicare beneficiaries. It presented a security vulnerability because it was directly based on the SSN, often including an alphanumeric suffix. If a Medicare card was compromised, the SSN was also compromised, raising the risk of identity theft.
In response to these security concerns, the Centers for Medicare & Medicaid Services (CMS) transitioned to the Medicare Beneficiary Identifier (MBI) in 2015. The MBI is an 11-character, randomly generated alphanumeric code that replaced the SSN-based HICN. Since January 1, 2020, providers must use the MBI for all Medicare transactions, including billing and eligibility checks. This shift ensures the MBI is a non-intelligent identifier, meaning its characters hold no hidden personal meaning, greatly reducing the potential for fraud and identity theft.
The Provider’s Tool: Internal Patient IDs
Distinct from government-issued identifiers is the Internal Patient ID, most commonly referred to as the Medical Record Number (MRN). This identifier is generated and used exclusively by a specific healthcare organization, such as a hospital system, clinic, or physician’s office. The MRN serves as the foundational link to all of a patient’s health data within that facility’s Electronic Health Record (EHR) system.
The MRN ensures that all clinical documentation, lab results, medication history, and imaging reports are accurately tracked under a single, unique patient profile. Because the MRN is facility-specific, a person will have a different MRN for every separate health system they visit. This internal code is primarily used for care coordination and patient safety, helping to prevent clinical errors.
Comparing Usage and Sensitivity
The various identifiers are requested at different points of the healthcare process and carry a vastly different level of risk if exposed. The SSN is the most sensitive number and is rarely required for medical care itself. Its use is confined to financial applications, government program enrollment, or identity matching. Sharing the SSN requires the highest caution due to its universal financial utility.
The MBI is required for submitting claims and verifying coverage for Medicare beneficiaries. While it must be protected, its utility is limited to the federal healthcare program, making its exposure a moderate risk compared to the SSN.
The MRN, or Patient ID, is routinely used by staff after check-in to ensure internal procedures and records are correctly matched. Since this number is not nationally standardized and is only functional within the issuing health system, it carries the lowest external risk. Its exposure does not grant access to financial accounts or government benefits, but it is essential for accurate internal care coordination.
Safeguarding Health Information
All identifiers connected to health data are protected under the Health Insurance Portability and Accountability Act (HIPAA). This federal regulation governs the privacy and security of Protected Health Information (PHI). HIPAA requires healthcare providers and business associates to implement safeguards to prevent unauthorized disclosure of patient information, including the MBI and MRN.
For individuals, protecting the SSN is the most important action. Patients should ask why a provider requires it before offering it. If a provider insists on the SSN for non-financial reasons, offering the last four digits or an alternative form of identification is a reasonable approach. Patients should treat their Medicare card with the MBI as a sensitive document, only sharing it with trusted providers for billing and eligibility.