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Medicare Forms Explained
Three forms cover most of the paperwork people actually run into: CMS-40B to sign up for Part B, CMS-L564 to prove you had employer coverage, and SSA-44 to appeal an income-related premium surcharge. Here is what each one does, where it goes, and a direct link to the real official form.
CMS-40B: Application for Enrollment in Medicare Part B
If you already have Part A and want to add Part B, whether during your Initial Enrollment Period, a Special Enrollment Period, or the General Enrollment Period, this is the form. It asks for basic identifying information and the date you want Part B coverage to start. You submit it to your local Social Security office by mail or fax, not to CMS directly.
CMS-L564: Request for Employment Information
This form is almost always filed together with CMS-40B. It proves that you had qualifying group health coverage through current employment (yours or a spouse's), which is what gives you a Part B Special Enrollment Period without a late penalty when that coverage ends. The form has two sections: you fill out Section A, and your employer fills out Section B confirming the coverage dates.
See the enrollment periods and penalties guide for how Special Enrollment Periods and late penalties actually work.
SSA-44: Medicare Income-Related Monthly Adjustment Amount Appeal
If your income is high enough to trigger an IRMAA surcharge on your Part B and Part D premiums, but your income has since dropped because of a specific life-changing event, SSA-44 lets you ask Social Security to use your more recent income instead of the two-year-old tax return IRMAA is normally based on.
Qualifying events include marriage, divorce or annulment, death of a spouse, work stoppage or reduction, loss of income-producing property, loss of pension income, and an employer settlement payment. You will need to include documentation of the event, such as a marriage certificate or a letter confirming your retirement date.
Use the IRMAA calculator first to see whether a surcharge likely applies to you at all before filing an appeal.
Where do these forms actually go?
CMS-40B and CMS-L564 both go to your local Social Security office, by mail, fax, or in person, never to CMS directly. SSA-44 can go to your local Social Security office or, in many cases, be submitted through your online Social Security account. Use the official Social Security office locator to confirm the right office for you, each of our county guides also lists the nearest confirmed office.
What about enrolling in a Medicare Advantage or Part D plan?
There is generally no separate CMS paper form for this. You enroll directly through the plan itself, through medicare.gov's Plan Finder, by calling 1-800-MEDICARE, or with help from a licensed agent. If a plan or someone representing a plan asks you to fill out a form that looks like an official government form for this purpose, confirm independently with medicare.gov before signing anything.
Common questions about Medicare forms
What is Form CMS-40B used for?
CMS-40B is the Application for Enrollment in Medicare Part B. You use it if you already have Part A and now want to add Part B, whether that is during your Initial Enrollment Period, a Special Enrollment Period, or the General Enrollment Period.
Where do I send Form CMS-40B?
You submit it to your local Social Security office, by mail or fax, not to CMS directly. Use the SSA office locator to find the right one, your own county guide also lists the nearest office.
What is Form CMS-L564 and when do I need it?
CMS-L564 is the Request for Employment Information. You file it together with CMS-40B when you are enrolling in Part B through a Special Enrollment Period based on current employer group health coverage, to prove that coverage existed and avoid a late enrollment penalty. You fill out your section, and your employer fills out theirs.
What is Form SSA-44 used for?
SSA-44 is used to request a reduction in your income-related monthly adjustment amount (IRMAA) after a qualifying life-changing event, such as marriage, divorce, death of a spouse, work stoppage or reduction, loss of income-producing property, loss of pension income, or an employer settlement payment.
How do I submit Form SSA-44?
You can mail or fax it to your local Social Security office, drop it off in person, or in many cases submit it through your online Social Security account. Include documentation of the life-changing event, such as a marriage certificate or a letter confirming your retirement date.
Is there a CMS paper form to enroll in a Medicare Advantage or Part D plan?
Generally no separate CMS paper form. Medicare Advantage and Part D enrollment is normally done directly through the plan itself, through medicare.gov’s Plan Finder, or by phone with 1-800-MEDICARE, not through a form like CMS-40B. A licensed agent can also walk you through enrollment for a specific plan.
Sources
Figures and form revisions verified 2026-10-01.