Medicare General Enrollment Period: Jan 1 to Mar 31, 2027, and What It Costs to Miss It
January 1 to March 31. If you missed your first chance to sign up for Medicare Part B and you don't qualify for a Special Enrollment Period, those three months are the only time each year you can add it. The next window opens January 1, 2027, and Part B starts on the first day of the month after you sign up, under 42 CFR 407.25(b)(3).
That start date is newer than a lot of people realize. Until 2023, anyone who signed up during the General Enrollment Period (GEP) waited until July 1 for coverage to begin, no matter whether they filed in January or March. A federal law passed in December 2020 changed that, and CMS wrote it into the regulations effective January 1, 2023. Older articles, and some people's memories, still describe the July wait. It's gone.
Source: 42 CFR 407.15 and 407.25; Medicare.gov, Avoid late enrollment penalties; CMS 2026 Part A and B premiums fact sheet.
Who the General Enrollment Period is for
Part B's window is set in 42 CFR 407.15: January through March of each year. The premium Part A rule, 42 CFR 406.21(c), uses the same January 1 to March 31 window and spells out who it's for: people "who failed to enroll during the initial enrollment period," people who didn't enroll during a special enrollment period, and people whose earlier Medicare entitlement ended. For Part B, in plain terms, that's three groups:
- You skipped Part B at 65 and had no job-based coverage. Your 7-month Initial Enrollment Period (three months before your birthday month, the birthday month, three months after) closed without a Part B sign-up.
- You had coverage that doesn't count. COBRA, retiree health coverage and individual or Marketplace coverage don't give you the Part B Special Enrollment Period that active employer coverage does. People find this out the hard way when COBRA ends.
- You missed the 8-month employer window. You had job-based coverage, it ended, and more than 8 months went by before you signed up.
It also covers Part A, but only for the small group who have to buy it. CMS says about 99% of people on Medicare pay no Part A premium. If that's you, you can sign up for premium-free Part A any time after 65, and it reaches back up to 6 months (never earlier than the month you turned 65), according to Medicare.gov. The GEP is really about Part B, and about premium Part A for people with fewer than 40 quarters of work.
Who doesn't need it? Anyone who qualifies for a Special Enrollment Period. Before you resign yourself to the GEP and a penalty, check whether one fits. The common ones: you're still covered by a group plan through your own or your spouse's current job, or that coverage or the job ended less than 8 months ago, whichever came first (details in my post on Medicare and employer coverage); you lost Medicaid; or you missed your sign-up because of a declared disaster, wrong information from an employer or health plan, or release from incarceration. Those exceptional-condition SEPs started January 1, 2023 and use form CMS-10797, per Medicare.gov.
When coverage starts if you sign up in 2027
The month you sign up decides everything. Here's the 2027 window under today's rule, next to what the same sign-up would have gotten you under the rule that applied through 2022.
| You sign up during | Part B starts (current rule) | Pre-2023 rule | Months saved |
|---|---|---|---|
| January 2027 | February 1, 2027 | July 1, 2027 | 5 |
| February 2027 | March 1, 2027 | July 1, 2027 | 4 |
| March 2027 | April 1, 2027 | July 1, 2027 | 3 |
| April 2027 or later | Wait for January 2028 (unless an SEP applies) | Same | None |
Source: 42 CFR 407.25(b)(1) and (b)(3); 42 CFR 406.21(c)(3); Medicare.gov, When does Medicare coverage start. Rows computed from the rule.
- Current rule (2023 on)
- Old rule (through 2022)
Source: 42 CFR 407.25(b); CMS final rule CMS-4199-F, 87 FR 66454.
Show the numbers
| Current rule (2023 on) | Old rule (through 2022) | |
|---|---|---|
| Sign up Jan | 1 | 6 |
| Sign up Feb | 1 | 5 |
| Sign up Mar | 1 | 4 |
The change came from section 120 of the Consolidated Appropriations Act, 2021. CMS implemented it in final rule CMS-4199-F, published November 3, 2022, effective January 1, 2023. The rule text describes the old system plainly: for people who enrolled during the GEP, "coverage is effective the July 1 following the month in which the individual enrolls."
What it means for you: there's no longer any advantage to waiting until March. Signing up on January 5 gets you Part B on February 1. Signing up on March 31 gets you April 1, two extra months without coverage, and those months still count toward the penalty. If you know you need Part B, file early in the window.
GEP, Open Enrollment and the MA Open Enrollment Period
Medicare has five windows people mix up, and two of them share the same dates. Here they are side by side.
| Window | Dates | Who it's for | What you can do |
|---|---|---|---|
| Initial Enrollment Period | 7 months around your 65th birthday month | People new to Medicare | Sign up for Part A and Part B; join a Medicare Advantage or drug plan |
| General Enrollment Period | Jan 1 to Mar 31 each year | People who missed their IEP and have no SEP | Sign up for Part B (and premium Part A); a late penalty may apply |
| Part B Special Enrollment Period (employer) | While covered by current-job group coverage, or 8 months after it or the job ends | People who delayed Part B because of active employer coverage | Sign up for Part B without a late penalty |
| Open Enrollment | Oct 15 to Dec 7 each year | Anyone with Medicare | Join, switch or drop a Medicare Advantage or drug plan; changes start Jan 1 |
| Medicare Advantage Open Enrollment | Jan 1 to Mar 31 each year | Only people already in a Medicare Advantage plan | One change: switch Medicare Advantage plans, or return to Original Medicare and add a drug plan |
Source: 42 CFR 407.14, 407.15, 422.62(a); Medicare & You 2027, pp. 17-19 and 75-76; Medicare.gov, When does Medicare coverage start.
The GEP and the Medicare Advantage Open Enrollment Period both run January 1 to March 31, and that's where the confusion comes from. They have nothing to do with each other. The GEP is for getting into Medicare Part B through Social Security. The MA Open Enrollment Period is for people who already have Medicare and already have a Medicare Advantage plan, and it allows one plan change. Per the 2027 handbook, it can't be used to move from Original Medicare into Medicare Advantage, or to join a stand-alone drug plan if you have Original Medicare.
The other mix-up is with fall Open Enrollment, which is running right now and ends December 7. Open Enrollment doesn't let you sign up for Part B. If you're missing Part B, no plan change this fall fixes that. And Medicare Advantage requires both Part A and Part B to join in the first place.
What waiting costs
The GEP lets you in. It doesn't forgive the delay. The Part B late enrollment penalty adds 10% of the standard premium for each full 12-month period you could have had Part B and didn't, and you usually pay it for as long as you have Part B, per Medicare.gov. Partial years don't count: the handbook's own example is someone whose Initial Enrollment Period ended in December 2021 and who signed up in March 2024. That's 27 months, but only two full 12-month periods, so 20%.
Premium Part A has its own penalty: 10% added to the premium, paid for twice the number of years you could have had it but didn't sign up. Eligible for two years and didn't buy it means four years of the higher premium.
The full rules, including how months are counted and what doesn't trigger a penalty, are in my post on Medicare late enrollment penalties. Here's the GEP-specific point, in a worked example.
Source: CMS 2026 premiums fact sheet; Medicare.gov penalty rules and rounding. Hypothetical, computed by Maru Insurance; ignores income-related adjustments.
Show the numbers
| Item | Value |
|---|---|
| No penalty (standard premium) | $202.90 |
| Sign up Feb 2027 (10% penalty) | $223.20 |
| Sign up Jan 2028 (20% penalty) | $243.50 |
Why 2026 numbers? CMS hasn't released the 2027 Part B premium and deductible yet. As of October 23 the 2027 fact sheet isn't posted; the 2026 amounts ($202.90 a month, $283 deductible) came out on November 14, 2025. Whatever the 2027 premium turns out to be, the penalty stays a percentage of it.
Drug coverage, Medicare Advantage and Medigap after the GEP
Getting Part B is step one. What you can add next, and when, depends on whether you already have Part A.
| Your situation | What the GEP opens up | Deadline to act |
|---|---|---|
| You have Part A and get Part B for the first time in the GEP | Join a Medicare Advantage plan (with or without drug coverage) | 2 months after adding Part B |
| You pay for Part A, or have Part B only, and sign up for Part B in the GEP | Join a Medicare drug plan; with Part A and Part B, a Medicare Advantage plan with drug coverage | From when you submit the application through the first 2 months of Part B |
| You want a Medigap policy | Washington OIC: best time is the first 6 months you're 65 or older and enrolled in Part B | Within the first 6 months you're 65+ and have Part B |
Source: Medicare & You 2027, pp. 75 and 85; 42 CFR 423.38(c)(16); Medicare.gov, Special Enrollment Periods; Washington OIC, Medigap coverage and costs.
Plan coverage starts the first of the month after the plan gets your request. Two months goes fast, especially if your Medicare card takes a few weeks to arrive, so start comparing as soon as you've filed with Social Security.
One gap to watch. If you already have premium-free Part A, you've been eligible for Part D since your Initial Enrollment Period. The handbook's GEP note for stand-alone drug plans is written for people who pay for Part A or have Part B only. If you have premium-free Part A and want a separate drug plan rather than Medicare Advantage, ask SHIBA or 1-800-MEDICARE which window applies to you before you assume. A Part D late penalty can apply on top of the Part B one if you've gone 63 or more days in a row without creditable drug coverage. The Part D rules and how drug coverage works here are on our Medicare Part D in Washington page.
On Medigap: the OIC says the best time to buy is "during the first six months in which you are age 65 or older and also enrolled in Part B." For someone who adds Part B through the GEP, that clock starts with the new Part B. Washington also lets people already in a Medigap Plan B through N switch to certain other plans at any time without health questions, but that's a switching right for existing Medigap policyholders, not a way in.
Washington: help and the ways around the GEP
Unbiased help. SHIBA, the Statewide Health Insurance Benefits Advisors program run by the Office of the Insurance Commissioner, has trained volunteers who help with Medicare questions at no cost. Call 800-562-6900, 8:30 a.m. to 4:30 p.m., Monday through Friday, or start at the OIC's SHIBA page. They're a good call before you file, to make sure you aren't missing an SEP.
Medicare Savings Programs and state buy-in. This is the one most people don't know about. Washington's Health Care Authority runs the Medicare Savings Programs: QMB pays Part A and Part B premiums plus deductibles and copays; SLMB and QI-1 pay the Part B premium. When a state pays Medicare premiums through a federal "buy-in" agreement, CMS has said the state can enroll eligible people in Medicare "without regard to Medicare enrollment periods" and late penalties. That language is in the 2022 final rule. Medicare.gov also says you generally won't owe a Part B penalty if you enroll in a Medicare Savings Program.
So if your income is limited (Washington has no asset test for these programs), apply for a Medicare Savings Program before you plan around the GEP. You may not have to wait for January at all. Income limits, how to apply and how buy-in works here are in my post on Medicare Savings Programs in Washington. Apply online at washingtonconnection.org, at a DSHS Community Services Office, or call HCA at 1-800-562-3022, ext. 16129, to have an application mailed to you (HCA flyer 22-500).
Still working? If you or your spouse have group coverage through a current job, you probably don't need the GEP. The 8-month Special Enrollment Period, form CMS-L564 and what counts as current employment are covered in Medicare and employer coverage.
For an overview of Parts A, B, C and D and how they fit together here, see our Medicare in Washington page.
How to sign up
You don't sign up for Part B with Medicare or with an insurance company. You sign up with Social Security (or the Railroad Retirement Board if you or your spouse worked for a railroad: 1-877-772-5772).
| If you... | Use | How it's sent |
|---|---|---|
| Already have Part A and want to add Part B in the GEP | Form CMS-40B, Request for Enrollment in Part B | Fax or mail to your local Social Security office |
| Have neither Part A nor Part B | Social Security application (online with a my Social Security account, by phone or at an office) | Online, phone 1-800-772-1213 (TTY 1-800-325-0778) or in person |
| Are using the employer Special Enrollment Period instead | CMS-40B plus CMS-L564, Request for Employment Information | Fax or mail to your local Social Security office |
| Qualify for an exceptional-condition SEP | Form CMS-10797 | Fax or mail to your local Social Security office |
Source: Medicare.gov, Enrollment forms; Medicare.gov, Ready to sign up for Part A and Part B; Medicare.gov, How do I sign up for Medicare.
Medicare.gov's instructions for adding Part B when you already have Part A are blunt: this route is "only available Jan 1 – March 31," and you should "only sign up this way if none of the other situations on this page apply to you." The CMS-L564 is not a GEP form. It's proof of employer coverage for the Special Enrollment Period. If you have that coverage history, use the SEP instead and skip the penalty.
A few practical things I'd do:
- File in January. Every month you wait inside the window is a month without Part B.
- Keep proof of the date. Keep a fax confirmation or mail it with tracking. Coverage turns on the month you enroll, so the date Social Security received your form matters.
- Write the two-month deadline on your calendar. If you want Medicare Advantage or a drug plan, the clock starts with Part B.
- Check your first premium notice. If a penalty is listed and you think an SEP or a Medicare Savings Program should have applied, ask Social Security about it.
Questions
When is the Medicare General Enrollment Period?
January 1 to March 31 every year. The next one runs January 1 to March 31, 2027. It's for people who missed their Initial Enrollment Period and don't qualify for a Special Enrollment Period.
When does coverage start if I sign up during the General Enrollment Period?
Part B starts the first day of the month after you sign up. Sign up in January 2027 and coverage starts February 1; sign up in March and it starts April 1. Before 2023, coverage didn't start until July 1.
Is the General Enrollment Period the same as the Medicare Advantage Open Enrollment Period?
No. They share the January 1 to March 31 dates, but the GEP is for signing up for Part B through Social Security. The Medicare Advantage Open Enrollment Period is only for people already in a Medicare Advantage plan, and allows one plan change.
Will I pay a penalty if I sign up during the General Enrollment Period?
Usually, if you went 12 full months or more without Part B when you could have had it. The penalty is 10% of the standard Part B premium for each full 12-month period, generally for as long as you have Part B.
Can I join a Medicare Advantage or drug plan after signing up for Part B in the GEP?
If you have Part A and get Part B for the first time in the GEP, you have 2 months after adding Part B to join a Medicare Advantage plan. If you pay for Part A or have Part B only, you can also join a Medicare drug plan within the first 2 months of Part B.
Federal Medicare rules and Social Security's determination in your case control what applies to you. Confirm your situation with Social Security, 1-800-MEDICARE, SHIBA or a licensed agent, and talk to an attorney for legal questions.
Sources
- eCFR: 42 CFR 407.15, general enrollment period (Part B)
- eCFR: 42 CFR 406.21, individual enrollment (premium Part A, GEP)
- eCFR: 42 CFR 407.25, beginning of entitlement, individual enrollment
- eCFR: 42 CFR 407.14, initial enrollment period
- eCFR: 42 CFR 408.24, individuals who enroll or reenroll after the IEP
- eCFR: 42 CFR 422.62, election of coverage under an MA plan
- eCFR: 42 CFR 423.38, enrollment periods for Part D
- Federal Register: CMS-4199-F final rule, 87 FR 66454 (Nov 3, 2022)
- Medicare.gov: When does Medicare coverage start
- Medicare.gov: Ready to sign up for Part A and Part B
- Medicare.gov: How do I sign up for Medicare
- Medicare.gov: Enrollment forms (CMS-40B, CMS-L564, CMS-10797)
- Medicare.gov: Avoid late enrollment penalties
- Medicare.gov: Joining a plan
- Medicare.gov: Special Enrollment Periods
- CMS: Medicare & You 2027 handbook
- CMS: 2026 Medicare Parts A and B premiums and deductibles fact sheet (Nov 14, 2025)
- Washington OIC: SHIBA Medicare help
- Washington OIC: Medigap (Medicare Supplement) coverage and costs
- Washington Health Care Authority: Medicare Savings Program
- Washington Health Care Authority: Medicare Savings Programs flyer, HCA 22-500 (05/26)
This article is for general educational purposes only and is not legal, tax or insurance advice. Coverage depends on the actual policy, its terms, conditions and exclusions, and state law. Maru Insurance · WA License (WAOIC) #1365574 · FL License #G363233 · NPN 22261820.