Are all Medicare numbers 11 digits?

You likely have two Medicare numbers because you were recently issued a new Medicare Beneficiary Identifier (MBI) due to security updates, or because you have a combination of Original Medicare, a Medicare Advantage plan, or past spousal/own work history numbers.

🔎 Common Reasons For Multiple Numbers

• 🛑 Security Reassignment: CMS periodically reassigns new MBIs (Medicare numbers) due to data breaches or fraud protection.
• 📋 Plan vs. Original ID: You might be confusing your Original Medicare number with a separate Medicare Advantage or Part D plan card ID.
• 👥 Spousal vs. Personal: You may have been assigned a number under your own Social Security number and another under a spouse's record.

💡 What You Should Do Next

• 📅 Check dates: Look at the issue dates or letters accompanying the cards to see which one is the most recent.
• 📞 Call support: Contact Official Medicare Support at 1-800-MEDICARE to verify which number is currently active.
• ⚠️ Shred the old card: Once you confirm your active number, securely destroy the outdated card to prevent billing errors or fraud.

An Australian Medicare card number has 10 digits on its own, or 11 digits when combined with an individual reference number.

Card Number Breakdown

• 10-Digit Card Number: The main number displayed across the top of the card. It consists of a 9-digit Medicare identifier (8-digit base plus a 1-digit checksum) followed by a 1-digit issue number.
• 11-Digit Combined Format: Often requested by Services Australia when linking your account online. This adds the 1-digit Individual Reference Number (IRN)—which sits next to a specific person's name—to the end of the 10-digit number.

The new Medicare ID, known as the Medicare Beneficiary Identifier (MBI), uses an 11-character alphanumeric format.

📊 MBI Structure Overview

• Length: Exactly 11 characters.
• Content: Numbers (0-9) and uppercase letters.
• Meaning: Randomly generated and "non-intelligent" with no hidden personal info.
• Excluded letters: S, L, O, I, B, and Z are left out to avoid confusion.

📌 Character Positions

• Character 1: Numeric (1-9).
• Character 2: Alphabetic (A-Z, excluding restricted letters).
• Character 3: Alphanumeric (0-9 or A-Z).
• Characters 4, 6, 7, 10, 11: Varies (numeric or alphabetic).
• Characters 5, 8, 9: Always alphabetic.

The Centers for Medicare & Medicaid Services (CMS) reissued new Medicare numbers (Medicare Beneficiary Identifiers) to approximately 1.3 million beneficiaries following data security incidents and compromised personal information.

Why New Numbers Are Issued

• Data Security Breaches: CMS sends replacement cards and new numbers as a protective measure when individual accounts or vendor databases experience fraudulent activity or compromise.
• Unchanged Benefits: Your coverage, benefits, and costs remain exactly the same with the new card.

What You Should Do

• Watch for Official Mail: CMS mails new paper cards with an explanatory letter.
• Update Providers: Give your new Medicare number to your doctors and healthcare providers right away to prevent billing or claim delays.
• Destroy the Old Card: Safely shred or cut up your old Medicare card once you receive and start using the new one.

Beware of Scammers

• No Activation Needed: Medicare cards are free and never require activation.
• No Phone Calls: Medicare will never call, text, or email you to ask for personal details or fees to send a new card.
• Verify Legitimate Mail: If you are unsure if a letter is real, call official support at 1-800-MEDICARE.

Original Medicare (Parts A and B) does not cover routine dental care, routine vision care, hearing aids, long-term custodial care, and health care received overseas.

Major Uncovered Services in 2026

• Most dental care: Original Medicare does not pay for routine cleanings, checkups, fillings, tooth extractions, root canals, or dentures.
• Routine vision care: Regular eye exams, eyeglasses, and contact lenses are excluded, though treatments for medical eye conditions like cataracts or glaucoma are covered.
• Hearing aids: Original Medicare does not cover hearing aids or routine exams used to fit them.
• Long-term care: Extended nursing home care or custodial care (help with daily personal activities like bathing or dressing) is not covered outside of limited short-term skilled nursing rehabilitation.
• Overseas coverage: Medical care received outside of the United States and its territories is generally excluded, with rare exceptions like emergencies on cruise ships close to a U.S. port.