What to Do If Someone Gets Your Medicare Number

Stop the fraud before it spreads

If you believe someone has your Medicare number, contact Medicare directly at 1-800-MEDICARE (1-800-633-4227) and tell them you suspect fraud. They can flag your account and watch for suspicious claims within hours. Do not wait to see if anything happens — the longer a thief uses your number, the harder it becomes to untangle the damage.

Medicare fraud using your number typically shows up as false claims for medical equipment, prescriptions, or services you never received. The thief bills Medicare (and sometimes your supplemental insurance) for these phantom services. Your out-of-pocket costs may jump because fraudulent claims count toward your deductible and out-of-pocket maximum, even though you did not receive the care.

The steps below assume you discovered the theft yourself — either by spotting unfamiliar charges on a bill, receiving an Explanation of Benefits (EOB) for services you did not get, or learning that someone used your number at a provider's office. If a data breach exposed your number, the organization that had the breach should notify you and offer free credit monitoring; follow their instructions in addition to the steps here.

Key Takeaways

Call Medicare at 1-800-MEDICARE when ready to report the suspected fraud and ask them to flag your account for monitoring.
Request a new Medicare number from Medicare; they will issue one by mail within two to three weeks, and your old number becomes inactive.
Review your Medicare Summary Notice or log into your online account to spot fraudulent claims, and report each one to Medicare in writing.
File a report with the Federal Trade Commission at IdentityTheft.gov so you have an official record if the fraud spreads to other accounts.
Place a fraud alert with the three credit bureaus (Equifax, Experian, TransUnion) to make it harder for a thief to open new accounts in your name.

Call Medicare and request a new number

When you call 1-800-MEDICARE, have your current Medicare number ready and explain that you suspect fraud. The representative will document the report in your account and can when ready flag it for investigation. Ask them to note the date and time of your call and the representative's name — you will need this for your written follow-up.

During the same call, ask for a new Medicare number. Medicare will mail you a new card with a different number within two to three weeks. Your old number will stop working for new claims after a set date (Medicare will tell you when). Existing claims under the old number may still process, so do not assume the old number is dead when ready.

If you use online tools like Medicare.gov or your plan's member portal, your login may stop working once your number changes. You will need to set up a new account using your new Medicare number once the card arrives. Keep your old card until the new one comes, because providers may still ask for it during the transition.

Document every fraudulent claim in writing

After you call, send a written letter to Medicare explaining what happened. Include the date you discovered the fraud, the date you called, the representative's name, and a list of any fraudulent claims you found. Attach copies of the EOBs or bills showing the false charges — do not send originals.

Mail your letter to the Medicare Administrative Contractor (MAC) that serves your state. You can find the correct address by calling 1-800-MEDICARE or visiting the Centers for Medicare & Medicaid Services (CMS) website. Include a cover note requesting written confirmation that they received your report.

If you spot additional fraudulent claims after you send your first letter, send a follow-up letter with the new information. Keep copies of everything you send and note the date you mailed it. Medicare typically investigates fraud reports within 30 to 60 days, though complex cases take longer.

File a report with the Federal Trade Commission

Go to IdentityTheft.gov and file a report about the Medicare fraud. The FTC will create an Identity Theft Report, which is an official government record that you can use if the fraud spreads to other accounts (credit cards, bank accounts, loans). Many creditors and financial institutions will take action faster if you show them an FTC Identity Theft Report.

The IdentityTheft.gov tool walks you through the fraud step by step and generates a customized recovery plan. You can print or read your report when ready. Save a copy and keep it with your important documents — you may need to show it to banks, credit card companies, or other providers if the thief tries to use your identity elsewhere.

Place a fraud alert with credit bureaus

Contact one of the three major credit bureaus — Equifax, Experian, or TransUnion — and ask them to place a fraud alert on your credit file. You only need to call one bureau; they are required to notify the other two. A fraud alert tells creditors to verify your identity before opening new accounts or making changes to existing ones.

A fraud alert lasts one year. If you want longer protection, you can request a credit freeze, which blocks creditors from viewing your credit report entirely unless you temporarily unlock it. A freeze is stronger but requires you to unfreeze your credit if you explore for a loan, credit card, or other credit in the future.

Here are the contact numbers for placing a fraud alert:

Equifax: 1-888-378-4329
Experian: 1-888-397-3742
TransUnion: 1-800-680-7289

Monitor your accounts and EOBs going forward

Check your Medicare Summary Notice (MSN) or online account every month for the next year. The MSN shows all claims submitted under your Medicare number. If you see services you did not receive, report them to Medicare when ready by calling 1-800-MEDICARE or by mail to your MAC.

If you have a Medicare Advantage plan or supplemental insurance, log into those accounts as well. Fraudulent claims may appear there too, and you want to catch them before they affect your deductible or out-of-pocket costs for the next year.

Set a phone reminder for the same day each month to review your accounts. This habit catches fraud early and gives you a paper trail if you need to dispute charges later.

What happens if the fraud continues after you report it

If you report fraud to Medicare and new fraudulent claims appear weeks or months later, the thief may have obtained additional personal information beyond your Medicare number. Call Medicare again and ask whether they have updated your account with the new fraud reports. Then file another report with the FTC at IdentityTheft.gov noting the new activity.

If the fraud spreads to your bank account, credit cards, or other government benefits (Social Security, Medicaid), you will need to report those separately to each institution. Your FTC Identity Theft Report will help you do this faster because you have an official record of the original fraud.

Keep all documentation — call logs, letters you sent, EOBs, and copies of your FTC report — in one folder. If you need to dispute charges or prove you reported the fraud, this file becomes your evidence.

Frequently Asked Questions

Will I have to pay for fraudulent claims billed to my Medicare?

No. Once Medicare confirms the claims are fraudulent, they will not count toward your deductible or out-of-pocket maximum, and you will not owe anything. However, if your supplemental insurance already paid a share of the fraudulent claim, you may need to contact them separately to request a refund.

How long does it take to get a new Medicare number?

Medicare mails your new card within two to three weeks of your request. Your old number stops working for new claims on a date Medicare will tell you, usually 30 days after the card is mailed. Existing claims under the old number may still process during the transition.

Do I need to notify my doctor's office about the fraud?

You do not have to, but it can help. If you call your regular providers and tell them your Medicare number was compromised and you have a new one, they can update their records and watch for any fraudulent claims submitted under the old number. This is especially useful if the thief used your number at a provider's office.

What if I do not know how the thief got my Medicare number?

You do not need to know the source to report the fraud. Report it to Medicare, the FTC, and your credit bureaus regardless. If a data breach exposed your information, the organization responsible will notify you separately and may offer free credit monitoring.

Can I get my old Medicare number back after I get a new one?

No. Once you are issued a new Medicare number, the old one is permanently retired. This is intentional — it prevents the thief from continuing to use it. Your new number is yours to keep for the rest of your life.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.