Enroll in Medicare Part B during a Special Enrollment Period

Apply through Social Security, not a private Medicare plan

This procedure concerns enrollment in Medicare Part B after delaying it because of qualifying group health coverage based on current employment. It is different from a Medicare Advantage or Part D Special Enrollment Period.

1. Confirm that the employment-based period applies

You may be able to enroll while you are still covered by a group health plan based on your current employment or your spouse's current employment, or during the limited period after the employment or coverage ends. The standard period generally ends eight months after the employment or group coverage ends, whichever occurs first.

COBRA and retiree coverage do not count as current-employment group coverage for this purpose. Do not wait for COBRA to end before checking the Part B deadline.

2. Choose an approved filing method

If you already have Part A, Social Security provides an online Part B application for many employment-based Special Enrollment Period cases. You may also submit the Application for Enrollment in Medicare Part B (CMS-40B) and the Request for Employment Information (CMS-L564) to a local Social Security office by fax or mail.

3. Obtain proof of employer coverage

Ask the employer to complete CMS-L564. If the employer cannot complete it, follow Social Security's current instructions for secondary evidence. Examples can include tax forms showing health premiums, pay records, insurance cards, benefit explanations, or other records that establish coverage based on current employment.

4. State the requested coverage month

Use the online application or the remarks section of CMS-40B to identify the month you want Part B coverage to begin, when the rules allow a choice. Confirm the effective date in the approval notice before ending other coverage.

5. Keep the filing record

Save the completed forms, supporting evidence, fax confirmation, mailing receipt, or online submission confirmation. Respond promptly if Social Security asks for missing information.

Exceptional circumstances

Medicare has other limited Special Enrollment Periods for circumstances such as losing Medicaid, release from incarceration, certain emergencies, or misinformation. Those cases can use different rules and Form CMS-10797. Do not use the employment-based instructions without checking the category that applies.