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What is an MBI Number?

What is an MBI Number? Understanding Your New Medicare Identifier

In an effort to enhance security and protect against identity theft, Medicare has introduced the Medicare Beneficiary Identifier (MBI) number. This new identifier replaces the old Health Insurance Claim Number (HICN), which was based on Social Security numbers. In this blog post, we will explore what an MBI number is, why it was introduced, and how it benefits you as a Medicare beneficiary.

What is an MBI Number?

An MBI number is a unique identifier assigned to each individual enrolled in Medicare. Unlike the previous HICN, which included a beneficiary’s Social Security number, the MBI is a randomly generated string of 11 characters. It consists of both numbers and uppercase letters, carefully designed to be easy to read and non-intrusive, containing no personal information.

Why Was the MBI Number Introduced?

The transition to MBI numbers was part of a broader initiative to improve security and safeguard the personal information of Medicare beneficiaries. Here are the main reasons for this change:

  1. Enhanced Security: The old HICN system used Social Security numbers, making it easier for identity thieves to exploit stolen Medicare cards. The new MBI system removes this risk by using a randomly generated identifier that contains no sensitive information.

  2. Identity Theft Protection: By removing Social Security numbers from Medicare cards, the risk of identity theft is significantly reduced. This change helps protect millions of Medicare beneficiaries from potential fraud.

  3. Compliance with Federal Mandates: The switch to MBIs complies with the Medicare Access and CHIP Reauthorization Act (MACRA) of 2015, which mandated the removal of Social Security numbers from all Medicare cards by April 2019.

The Format of the MBI Number

The MBI number is designed to be user-friendly and secure. It follows a specific format: 11 characters that include both numbers and uppercase letters. Here’s a breakdown of its structure:

  • The first character is a letter.
  • Characters 2 through 11 are a mix of letters and numbers.

This structure ensures that the MBI is unique to each beneficiary while maintaining a format that is easy to read and understand.

Using Your MBI Number

As a Medicare beneficiary, your MBI number is essential for all your Medicare-related activities. Here’s what you need to know about using your MBI:

  • On Your Medicare Card: Your MBI number is prominently displayed on your new Medicare card. You should keep this card safe and carry it with you to medical appointments.
  • Healthcare Providers: When you visit healthcare providers, they will use your MBI number to verify your eligibility and process claims.
  • Medicare Communications: Use your MBI number whenever you communicate with Medicare, whether over the phone, online, or through mail.

Benefits of the MBI Number

The introduction of the MBI number offers several significant benefits:

  • Increased Privacy: By not including your Social Security number, the MBI enhances your privacy and reduces the risk of identity theft.
  • Simplified Claims Processing: The unique format of the MBI makes it easier for healthcare providers to process claims accurately and efficiently.
  • Improved Security: The random generation of MBI numbers ensures that no personal information is embedded within the identifier, adding an extra layer of security.

Transition to MBI Numbers

The transition from HICN to MBI began in April 2018 and was completed by January 2020. During this period, beneficiaries received their new Medicare cards in the mail. If you haven’t received your new card or have misplaced it, you can request a replacement through the Medicare website or by calling Medicare directly.


The MBI number represents a significant step forward in protecting the personal information and identities of Medicare beneficiaries. By understanding what an MBI number is and how to use it, you can take full advantage of its benefits and ensure your Medicare interactions are secure and efficient. Keep your new Medicare card safe, and remember that your MBI number is your key to accessing Medicare services without compromising your personal information.

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What is an MBI Number

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