Enrolling in Medicare is usually straightforward, but the documents you need depend on how you qualify, whether you are enrolling for the first time, whether you delayed Part B because you had employer coverage, and whether you are joining Original Medicare or a private Medicare plan.
For many people turning 65, Medicare enrollment can be completed online through the Social Security Administration without uploading a large stack of paperwork. Social Security may already have the information needed to confirm your age and eligibility.
Other applicants may need to provide a birth certificate, proof of U.S. citizenship or lawful immigration status, employment information, employer health coverage records, or specific Medicare enrollment forms.
This guide explains the documents required for Medicare enrollment as of October 2026, including what you need for Part A, Part B, a Special Enrollment Period, Medicare Advantage, and Part D.
Important: This guide is for individuals enrolling in Medicare coverage. Medicare enrollment for doctors, hospitals, suppliers, and other healthcare providers uses a completely different CMS provider-enrollment process.
Quick Answer: What Documents Do You Need to Enroll in Medicare?
For a standard Medicare application, start by having the following information available:
| Document or Information | When You May Need It |
|---|---|
| Social Security number | Nearly all Medicare applications |
| Date and place of birth | Standard enrollment |
| Birth certificate or other proof of age | If Social Security needs age verification |
| Proof of U.S. citizenship | If not already established in SSA records |
| Proof of lawful immigration status | Certain non-U.S.-born applicants |
| Employer health insurance information | If you have or had group health coverage |
| Medicare number | If you already have Part A and are adding Part B |
| CMS-40B | Commonly used when adding Part B after Part A |
| CMS-L564 | Special Enrollment Period based on current employment coverage |
| Proof of previous employer coverage | If employer cannot complete CMS-L564 |
| CMS-10797 | Certain exceptional-condition Special Enrollment Periods |
| Medicare card | Usually needed when joining Medicare Advantage or Part D |
| Part A and Part B effective dates | Medicare Advantage/Part D enrollment |
| Military records | SSA may request them for certain older military-service records |
| W-2 or self-employment tax return | May be requested depending on the Social Security application |
You may not need to submit every item in this table. Social Security determines what evidence is necessary based on your record and how you qualify.
SSA specifically says applicants should not delay applying simply because they do not yet have every requested document. Missing documents may often be provided later.
Do You Actually Need to Apply for Medicare?
Before gathering documents, determine whether you need to submit an application at all.
Some people are enrolled automatically.
If you are already receiving Social Security retirement benefits at least four months before turning 65, Medicare generally enrolls you automatically in Part A and Part B when you turn 65. Medicare says your welcome package and Medicare card are normally mailed about three months before coverage begins.
If you receive Social Security disability benefits, Medicare generally begins automatically after 24 months of disability benefits. People receiving disability benefits because of ALS can receive Medicare automatically without that 24-month waiting period.
If you are not receiving Social Security benefits before 65, you generally need to actively enroll through Social Security.
Documents Required for First-Time Medicare Enrollment
If you are turning 65 and need to enroll yourself, you usually apply for Medicare Part A and Part B through the Social Security Administration, not directly through Medicare.
SSA’s Medicare application asks for basic personal and health-insurance information. Current SSA guidance says applicants should be prepared to provide their Social Security number, birthplace, and information about current or previous group health coverage.
1. Social Security Number
Your Social Security number is one of the core identifiers used during Medicare enrollment.
You generally do not need to submit a physical Social Security card if SSA can verify your information electronically, although Social Security may request additional evidence if its records are incomplete or inconsistent.
2. Proof of Age
Social Security may ask for proof of your date of birth.
The preferred document is generally an original birth certificate or a copy certified by the agency that issued it.
SSA may also accept other evidence when an early birth record is unavailable. Examples can include older school, hospital, census, vaccination, insurance, or religious records.
Do not assume that an ordinary photocopy of a birth certificate will be acceptable. SSA states that for most identity, age, or citizenship evidence it needs the original document or a copy certified by the issuing agency, rather than a photocopy or notarized copy.
3. Proof of U.S. Citizenship
If Social Security has already verified your U.S. citizenship from an earlier claim, you normally do not need to prove it again.
If citizenship has not previously been established in SSA records, you may be asked for documentation.
Depending on your circumstances, acceptable evidence can include documents such as a:
| Possible Citizenship Document | Typical Use |
|---|---|
| U.S. birth certificate | U.S.-born citizen |
| U.S. passport | Citizenship and identity evidence |
| Certificate of Naturalization | Naturalized U.S. citizen |
| Certificate of Citizenship | Certain citizens born abroad |
| Consular Report of Birth Abroad | Certain U.S. citizens born outside the U.S. |
SSA confirms that people not born in the United States may be asked to provide proof of U.S. citizenship or lawful alien status when applying for Medicare or Social Security benefits.
4. Immigration or Lawful Residency Documents
Medicare eligibility can also depend on citizenship or lawful residency requirements.
If you were not born in the United States and SSA does not already have the necessary information, you may need to show documentation establishing your immigration or lawful residency status.
The exact document depends on your immigration status.
A Permanent Resident Card, commonly called a Green Card, is one example of a Department of Homeland Security document SSA may use when verifying lawful immigration status.
Do not mail important DHS documents unless specifically instructed
SSA cautions applicants against mailing foreign birth records or immigration documents that are difficult to replace. When originals must be inspected, taking them to a Social Security office may be safer.
5. Health Insurance Information
If you currently have health insurance—or had employer insurance after age 65—Social Security may ask for coverage details.
SSA’s Medicare sign-up guidance currently asks applicants to be ready with:
| Information | Example |
|---|---|
| Current group health plan | Employer-sponsored insurance |
| Coverage start date | Month/year insurance began |
| Coverage end date | If coverage has ended |
| Group coverage after age 65 | Dates of employer coverage after Medicare eligibility |
| Employment information | Employer connected to the health plan |
These details become especially important when you delay Medicare Part B because you or your spouse are still working.
Documents Required to Enroll in Medicare Part B After You Already Have Part A
This is one of the most common Medicare enrollment situations.
Suppose you enrolled in premium-free Part A at 65 but delayed Part B because you were still working and covered by an employer health plan.
When that coverage ends, you may need to enroll in Part B.
If you already have Part A, one of the main forms is:
CMS-40B — Application for Enrollment in Medicare Part B
CMS-40B is specifically used by people who already have Medicare Part A and want to enroll in Part B. CMS’s current form page lists the latest CMS-40B revision as July 1, 2025, with OMB approval through July 31, 2028.
The form requests basic identifying and enrollment information, including your Medicare-related information and requested Part B enrollment.
If you are enrolling through a Special Enrollment Period based on employment coverage, CMS-40B is normally paired with another important form: CMS-L564.
CMS-L564: Proof of Employer Health Coverage
CMS-L564 — Request for Employment Information is used to document that you had group health plan coverage based on current employment.
This form can be critical when you delayed Part B because you or your spouse continued working.
CMS says the form is intended to establish eligibility for the Medicare Special Enrollment Period based on employer group health plan coverage.
The process generally works like this:
| CMS-L564 Section | Who Completes It |
|---|---|
| Section A | Medicare applicant |
| Section B | Employer |
The employer confirms information such as when employment began, when health coverage began, and when coverage or employment ended.
What If Your Employer Cannot Complete CMS-L564?
This happens more often than people expect.
A former employer may have closed, merged, changed payroll providers, lost older records, or simply be slow to respond.
Medicare states that if the employer cannot complete CMS-L564, the applicant can complete Section B as accurately as possible without signing for the employer and provide other proof of job-based insurance.
SSA lists several types of secondary evidence that may help establish employer health coverage:
| Alternative Evidence | What It Can Show |
|---|---|
| W-2 showing pre-tax medical contributions | Employer-sponsored health coverage |
| Pay stubs with insurance deductions | Premiums paid through employment |
| Income tax returns showing insurance premiums | Evidence of coverage/payment |
| Health insurance card with effective date | Coverage and policy dates |
| Explanation of Benefits | Use of employer group health insurance |
| Insurance premium receipts/statements | Proof premiums were paid |
SSA explicitly recognizes these types of documents when an employer cannot provide the usual CMS-L564 evidence.
This can prevent an unavailable former employer from becoming an unnecessary roadblock to Medicare enrollment.
The 8-Month Medicare Part B Special Enrollment Period
People who delay Part B because they have qualifying employer-based coverage may generally enroll while still covered or during an 8-month Special Enrollment Period after employment or qualifying employer coverage ends, depending on which occurs first.
This rule is important because not every kind of health insurance gives you the same protection.
For example, choosing COBRA after leaving a job does not generally stop or restart the Medicare Part B 8-month Special Enrollment Period. Medicare states that the eight-month window generally starts when employment ends even if you continue coverage through COBRA.
That distinction can affect both coverage gaps and possible late-enrollment penalties.
Medicare Enrollment Forms at a Glance
Different Medicare circumstances use different forms.
| Form | Primary Purpose |
|---|---|
| CMS-18-F-5 | Part A enrollment when you do not already have Part A; may also be used for Part B |
| CMS-40B | Enroll in Part B when you already have Part A |
| CMS-L564 | Prove qualifying employer group health coverage for an employment-based SEP |
| CMS-4040 | Certain people not entitled to Social Security or Railroad Retirement benefits enrolling in Part B |
| CMS-43 | Medicare enrollment related to End-Stage Renal Disease |
| CMS-10797 | Part A/Part B Special Enrollment Period for qualifying exceptional circumstances |
| CMS-10798 | Part B immunosuppressive drug coverage |
CMS’s current Original Medicare enrollment guidance identifies these forms for different Part A and Part B enrollment situations.
Do not choose a Medicare form simply because its title sounds close to your situation. The correct form depends on whether you already have Part A, why you delayed enrollment, and which enrollment period you are using.
CMS-10797: Exceptional Circumstances Special Enrollment Period
Medicare also provides Special Enrollment Periods for certain exceptional circumstances.
Examples may include qualifying situations where circumstances outside your control prevented timely Medicare enrollment.
CMS says eligible applicants may use CMS-10797, Application for Medicare Part A & Part B — Special Enrollment Period (Exceptional Conditions).
CMS also makes clear that an exceptional-circumstances SEP is not intended simply for someone who forgot to enroll or did not know about the enrollment requirement. SSA evaluates these cases based on the specific circumstances.
Supporting documentation or a written attestation may be required to show why the person could not enroll on time.
Documents Required During the Medicare Initial Enrollment Period
For most people who become eligible at 65, the Initial Enrollment Period lasts seven months:
3 months before the month you turn 65 + your birthday month + 3 months after your birthday month.
If you need to actively apply, your practical preparation checklist is usually much simpler than the Special Enrollment Period paperwork.
You should have ready:
- Social Security number
- Date and place of birth
- Citizenship or immigration information
- Current health insurance information
- Employer information if covered through a job
- Birth/citizenship evidence if SSA asks for verification
If Social Security already has verified proof of your age and citizenship from another benefit claim, you generally do not have to submit the same documents again.
When Does Medicare Coverage Start?
Documentation is only half the process. Timing matters.
For most people qualifying at age 65, if you enroll in Part B before the month you turn 65, coverage normally begins the month you turn 65.
If you enroll during your birthday month or during the following three months, coverage generally begins the next month.
If you miss your Initial Enrollment Period and do not qualify for a Special Enrollment Period, the General Enrollment Period runs January 1 through March 31 each year, with coverage generally beginning the month after you enroll.
Documents Needed for Medicare Advantage Enrollment
Medicare Advantage, also called Medicare Part C, works differently from Original Medicare enrollment.
You first need Medicare Part A and Part B.
To join a Medicare Advantage plan, Medicare says you generally need your:
| Information | Where to Find It |
|---|---|
| Medicare Number | Red, white, and blue Medicare card |
| Part A coverage start date | Medicare card |
| Part B coverage start date | Medicare card |
| Residential/service-area information | Your current address |
You must have both Part A and Part B to join a Medicare Advantage plan.
You generally do not need to resubmit your birth certificate or citizenship documentation to the Medicare Advantage insurer if Medicare eligibility has already been established. The plan uses your Medicare information to process enrollment.
Documents Needed for Medicare Part D Enrollment
Medicare Part D provides prescription drug coverage.
To join a stand-alone Medicare drug plan, you generally need to have Part A or Part B and provide your Medicare enrollment information.
Your Medicare card contains the most important details: your Medicare Number and coverage effective date.
You may also be asked for personal and contact information by the insurance plan.
Enrollment in a Medicare Advantage or Part D plan must occur during an eligible enrollment period.
Do You Need Your Medicare Card to Enroll in a Plan?
Usually, yes.
Once Social Security completes your Original Medicare enrollment, you receive a red, white, and blue Medicare card containing your unique Medicare Number and Part A/Part B effective dates.
Medicare specifically states that this information is needed to create a Medicare.gov account, join a Medicare plan, or purchase supplemental insurance.
Your Medicare Number is different from your Social Security number.
Medicare Enrollment When You Have a Disability
People under 65 can qualify for Medicare under certain circumstances.
If you are receiving qualifying Social Security disability benefits, Medicare generally begins automatically after you have received disability benefits for 24 months.
Because enrollment may be automatic, you may not need to submit a separate standard Medicare application.
However, special circumstances can require additional documentation, particularly when coordinating employer coverage or enrolling through a Special Enrollment Period.
For a disabled individual relying on current employment-based coverage, CMS-L564 can also apply. CMS notes that disabled applicants may have qualifying large-group health coverage through their own employment, a spouse’s employment, or certain family-member employment.
Medicare Enrollment for ALS
If you have ALS and qualify for Social Security disability benefits, Medicare enrollment rules are different from the usual disability waiting period.
Medicare says eligible individuals with ALS receive Medicare automatically when disability benefits begin rather than waiting 24 months.
The underlying disability-benefit process involves its own medical and Social Security documentation, but a separate routine age-65 Medicare application generally is not the enrollment path.
Medicare Enrollment for End-Stage Renal Disease
People with End-Stage Renal Disease (ESRD) may qualify for Medicare before age 65.
CMS identifies Form CMS-43 for individuals with ESRD enrolling in Part A and Part B.
ESRD enrollment rules depend on circumstances such as dialysis, kidney transplant status, and eligibility history, so these applications should be handled according to the specific Social Security and Medicare instructions for ESRD rather than using a generic age-65 checklist.
What Documents Should You Bring to a Social Security Office?
If you are handling Medicare enrollment in person, it can save time to bring the documents most likely to be relevant to your situation.
A practical file might include your Social Security information, government-issued identification, birth evidence if requested, citizenship or immigration documents if SSA has not already verified them, employer insurance records, Medicare card if you already have Part A, and any CMS forms related to your enrollment situation.
If you are enrolling after employer coverage, bring CMS-40B and CMS-L564 or the alternative insurance evidence that applies to your case.
Do not assume everything must be submitted. SSA may already have some records electronically.
Original Documents vs. Photocopies
This detail causes a lot of Medicare enrollment confusion.
SSA may accept photocopies of certain financial or employment documents, such as W-2s and some tax records.
However, for many identity, age, citizenship, and immigration records, Social Security generally requires original documents or copies certified by the issuing agency rather than ordinary photocopies or notarized copies.
If you are unsure whether to mail an irreplaceable original document, contact SSA first. Social Security specifically advises applicants not to mail certain foreign birth records or DHS immigration documents and instead to bring them to an office for inspection.
What If You Cannot Find Your Birth Certificate?
Do not automatically delay your Medicare application.
SSA states that applicants should still submit their application even when some documents are missing.
Social Security may be able to verify birth information electronically through a state Bureau of Vital Statistics or accept other evidence of age when the usual birth record is unavailable.
Delaying an application while searching for documents can be more problematic than filing on time and providing missing evidence afterward.
Documents Required for Medicare Enrollment by Situation
This comparison makes the process easier to understand.
| Your Situation | What You Should Usually Have Ready |
|---|---|
| Turning 65 and actively enrolling | SSN, birth details, insurance information, citizenship/residency evidence if requested |
| Already receiving Social Security before 65 | Usually automatic enrollment; review Medicare card/welcome package |
| Have Part A and need Part B | Medicare Number + CMS-40B |
| Leaving employer coverage after 65 | CMS-40B + CMS-L564 |
| Employer cannot complete CMS-L564 | CMS-40B + CMS-L564 information + secondary insurance/employment evidence |
| Missed enrollment because of qualifying exceptional circumstances | CMS-10797 + supporting evidence/attestation |
| Joining Medicare Advantage | Medicare Number + Part A and Part B effective dates |
| Joining Part D | Medicare Number + Part A or Part B enrollment information |
| ESRD enrollment | Specialized Medicare process, including CMS-43 where applicable |
| Disability-based Medicare | Often automatic after qualifying disability-benefit period |
| ALS | Medicare generally automatic with qualifying disability benefits |
Common Medicare Enrollment Document Mistakes
Assuming Everyone Needs a Birth Certificate
SSA may already have your age verified.
A birth certificate is something Social Security may request, not necessarily a document every Medicare applicant must submit again.
Waiting for Every Document Before Applying
SSA specifically tells applicants not to postpone filing simply because one document is missing.
Using CMS-40B for a First-Time Part A Application
CMS-40B is primarily for someone who already has Part A and wants Part B. If you do not have Part A, Medicare directs you to Social Security for initial enrollment instead. CMS
Forgetting CMS-L564 After Employer Coverage
If you delayed Part B because you had health insurance through current employment, CMS-L564 is often one of the most important documents in the Special Enrollment Period process.
Assuming COBRA Gives You Unlimited Time to Enroll
It does not.
The eight-month Part B Special Enrollment Period generally begins when employment or qualifying job-based coverage ends; COBRA does not normally extend that deadline.
Mailing Irreplaceable Immigration Documents
SSA advises against mailing certain foreign birth or DHS immigration records because replacement can be difficult.
Confusing Medicare and Social Security
You sign up for Medicare Part A and Part B through Social Security. After enrollment, Medicare handles many coverage-related matters, while private insurers handle enrollment in their Medicare Advantage or Part D plans.
Medicare Enrollment Timeline at Age 65
Your Initial Enrollment Period normally spans seven months:
| Timeline | Enrollment Window |
|---|---|
| 3 months before turning 65 | Enrollment open |
| 2 months before | Enrollment open |
| 1 month before | Enrollment open |
| Month you turn 65 | Enrollment open |
| 1 month after | Enrollment open |
| 2 months after | Enrollment open |
| 3 months after | Initial Enrollment Period ends |
For Part B and premium Part A, enrolling before your birthday month generally allows coverage to begin in your birthday month. Enrolling during your birthday month or in one of the next three months generally starts coverage the following month.
Medicare Document Checklist Before You Apply
A simple way to prepare is to separate your paperwork into four categories:
Identity and eligibility: Social Security number, birth information, citizenship or lawful-residency evidence if requested.
Health insurance: Current and previous group plan names, coverage dates, insurance cards, employer information.
Special Enrollment Period: CMS-40B, CMS-L564, and supporting proof of job-based coverage when applicable.
Post-Medicare plan enrollment: Medicare card, Medicare Number, Part A effective date, and Part B effective date.
This approach avoids bringing unrelated documents while making sure the paperwork most likely to delay an application is ready.
Frequently Asked Questions About Medicare Enrollment Documents
What documents do I need to enroll in Medicare at age 65?
Most applicants should be ready with their Social Security number, date and place of birth, health insurance information, and citizenship or immigration information. SSA may request supporting documents such as a birth certificate or proof of citizenship if those facts have not already been verified.
Do I need my birth certificate to apply for Medicare?
Not always. Social Security may already have proof of your age. If SSA asks for age verification, an original birth certificate or a copy certified by the issuing agency is generally preferred.
Do I need my Social Security card to enroll in Medicare?
You need your Social Security number, but a physical Social Security card is not necessarily required for every application. SSA may request additional evidence when it cannot verify information electronically.
What documents do I need for Medicare Part B?
If you already have Part A and want Part B, CMS-40B is the standard Part B enrollment form. If you delayed Part B because you had qualifying employer coverage, CMS-L564 is generally submitted as proof of that coverage.
What documents prove employer coverage for Medicare?
CMS-L564 is the primary employment-information form. If your employer cannot complete it, SSA may accept evidence such as W-2 records showing medical contributions, pay stubs showing insurance deductions, insurance cards with effective dates, Explanation of Benefits statements, tax records, or premium receipts.
Do I need proof of citizenship for Medicare?
Possibly. If SSA has already established your citizenship or lawful status, you generally do not need to provide it again. Otherwise, Social Security may request appropriate proof.
Can I enroll in Medicare without all my documents?
Yes, you should generally file on time rather than delay an application solely because a requested document is missing. SSA says missing documents can often be provided later or verified through other sources.
What information is needed to join Medicare Advantage?
You generally need your Medicare Number and your Part A and Part B coverage start dates. You must have both Part A and Part B to enroll in Medicare Advantage.
What information is needed for Medicare Part D?
A Medicare drug plan generally requires your Medicare information. You need Medicare Part A or Part B to join a stand-alone Part D plan.
Is CMS-L564 required for everyone enrolling in Medicare?
No. It is primarily used to document qualifying employer group health coverage when enrolling through a Special Enrollment Period based on current employment.
Can I fill out CMS-L564 myself?
You complete Section A. Normally, your employer completes Section B. If the employer cannot do so, Medicare and SSA provide procedures for submitting the form with alternative evidence of employment-based health coverage.
Where do I submit Medicare Part B enrollment forms?
CMS-40B and CMS-L564 can be sent to your local Social Security office according to the applicable instructions. Medicare also offers online Part B enrollment options for certain situations.
Final Takeaway
The documents required for Medicare enrollment depend much more on your situation than on your age alone.
For a straightforward first-time Medicare application, you may need little more than your Social Security information, birth details, insurance history, and any proof SSA cannot verify electronically.
If you delayed Part B because you had employer coverage, documentation becomes more important. CMS-40B and CMS-L564, along with evidence of employer health coverage when necessary, are often central to the process.
If you are joining a Medicare Advantage or Part D plan after Original Medicare enrollment, the most important document is usually your Medicare card, because it contains your Medicare Number and coverage effective dates.
The best rule is simple: apply during the correct enrollment period, gather documentation specific to your situation, and do not delay a timely application just because one supporting document is temporarily unavailable.
Updated: October 2026. CMS and Social Security forms and enrollment procedures can change. Anyone applying in 2027 should verify the current version of the applicable form and current enrollment instructions before submitting an application.