What is an mbi number?

An MBI number (Medicare Beneficiary Identifier) is the unique identifier issued by Medicare to replace the old SSN-based Health Insurance Claim Number (HICN). It’s essential for billing, claims, and healthcare administration.

1. Why Medicare Uses an MBI Number

• The MBI is a randomly generated, 11-character alphanumeric ID assigned to each Medicare enrollee. It does not contain any embedded personal information like Social Security numbers.

• Since January 1, 2020, the MBI has been the required identifier for all Medicare transactions—including billing and claim filings.

• This change enhances privacy and helps reduce identity theft and fraud in the healthcare system.

2. MBI Format and Rules

• The MBI consists of 11 characters—a mix of numbers and uppercase letters.

• It never includes the letters S, L, O, I, B, or Z to avoid confusion.

• The format generally follows this structure:

  • Positions 1, 4, 7, 10–11: digits

  • Positions 2, 5, 8–9: letters

  • Positions 3 & 6: either a letter or a digit

• MBIs are entered without dashes or spaces in all systems.

3. How and Why You’ll Use an MBI

• Your MBI is printed on your Medicare card and used in all Medicare communications.

• Healthcare providers, pharmacies, and insurers must use the MBI when submitting claims.

• Using outdated numbers will result in denied claims or delays in processing.

4. Protecting and Managing Your MBI

• Treat your MBI like sensitive personal information—only share it with trusted medical providers.

• If you lose your Medicare card, you can request a new one through Medicare services or access your MBI online.

• Never post or email your MBI unless you’re using a secure, trusted channel.

5. MBI vs. Old HICN—Key Differences

Final Takeaway

An MBI number is the secure, randomly generated Medicare Beneficiary Identifier assigned to every Medicare enrollee. It must be used in place of the HICN for all Medicare-related billing and claims. Understanding its format, use, and protection requirements ensures smoother healthcare processing.

Need help verifying MBI numbers or navigating Medicare coverage?
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