Medicare General Enrollment Period rules matter most to people who assumed someone else would sign them up. Turning 65 does not enroll you unless you already collect Social Security or Railroad Retirement, and the 7-month Initial Enrollment Period (3 months before your birthday month, the month itself, and 3 months after) closes without a reminder. Late enrollees who never held qualifying employer coverage end up in the General Enrollment Period, which runs 3 months, January 1 through March 31, every year. The 2026 window closed on March 31, 2026, so anyone reading this in the fall of 2026 has one option that avoids a longer gap: prepare now and apply the first week of January 2027. Medicare.gov and Social Security both confirm that coverage under the GEP starts the month after you sign up, not retroactively. That change took effect in 2023; before it, GEP coverage started July 1, which left many people uncovered for months. The catch is cost. Part B carries a 10% surcharge for each full 12-month period you could have enrolled, and the 2026 standard Part B premium is $202.90 per month, so the penalty compounds on a base that rises every year.
Medicare late enrollment is not one decision but four, and each part has its own clock. Part A is premium-free for most people with 40 quarters of work, so late enrollment costs nothing there and Part A can start up to 6 months back. Part B carries the lifetime penalty. Part D drug coverage carries a separate 1% per month penalty after 63 days without creditable coverage. Medigap guaranteed issue runs 6 months from the month you are 65 or older and enrolled in Part B. This guide walks through six steps for the January 1 to March 31, 2027 window, shows how a COBRA plan or retiree plan can quietly cost you the penalty exemption, and explains when a Marketplace SEP or state Medicare Savings Program is the better route. Read the Medicare eligibility rules for 2026 first, then confirm whether an 8-month Special Enrollment Period already covers you before you commit to waiting for January.
6 Steps to Get Coverage
Common Mistakes That Cost People Thousands
Late Medicare enrollees repeat the same five errors, and most carry permanent costs in 2026 and beyond:
- Waiting for the wrong month. The GEP only runs January 1 through March 31, and an April application sits until the next January, adding a full year of penalty.
- Assuming COBRA or retiree coverage counts. Neither creates a Special Enrollment Period, so the 10% per year Part B penalty applies once you finally enroll.
- Skipping Part D. Going 63 days or more without creditable drug coverage adds a 1% per month Part D penalty for life, even if you take no prescriptions today.
- Keeping a subsidized Marketplace plan after Medicare starts. Premium tax credits end when you become eligible for premium-free Part A, and you may owe repayment on your Form 1095-A reconciliation.
- Not asking about a Medicare Savings Program. State programs can pay your Part B premium and, in many states, the buy-in also removes the late penalty, but you must apply.
How the 2026 Part B Late Penalty Is Calculated
Part B late enrollment penalty math starts with the number of full 12-month periods between the end of your Initial Enrollment Period and the month Part B begins. Each full period adds 10% to the standard premium, and partial years do not count. The 2026 standard Part B premium is $202.90 per month, so one full year late adds about $20.29 per month, two years adds about $40.58, and five years adds about $101.45 per month. Medicare recalculates the penalty against each year's standard premium, so the dollar amount rises whenever the base premium rises. Medicare.gov states the penalty lasts as long as you have Part B. There is one exception that matters: if you qualify for a state Medicare Savings Program, the state can pay the premium, and some states also absorb the penalty. Check the 2026 CMS premium fact sheet for the current base figure before you calculate.
Part B late penalty by years delayed, 2026 standard premium of $202.90| Full 12-month periods late | Penalty percentage | Extra monthly cost in 2026 |
|---|
| 1 | 10% | $20.29 |
| 2 | 20% | $40.58 |
| 3 | 30% | $60.87 |
| 5 | 50% | $101.45 |
Figures use the 2026 standard Part B premium and round to the nearest cent. The penalty is recalculated against each future year's standard premium.
Source: CMS 2026 Medicare Parts A and B premiums fact sheet; Medicare.gov late enrollment penalties
Why COBRA and Retiree Plans Do Not Stop the Penalty Clock in 2026
COBRA continuation coverage feels like employer coverage, and that is exactly why it traps people. Medicare treats only active employment coverage as a qualifying life event for the Part B exemption: you, or your spouse, must be currently working and covered by an employer with 20 or more employees. COBRA, retiree health plans, and individual Marketplace plans do not qualify, so the 8-month Special Enrollment Period never starts for people who hold them. A person who turns 65 in 2026, leaves work, and keeps COBRA for 18 months has been burning penalty months the whole time. Federal COBRA also allows an election window of 60 days after the qualifying event, and monthly costs run about $400 to $900 for an individual in 2026, at 102% of the full premium. When you become eligible for Medicare, COBRA can end early, so time your Part B start before the last day of any coverage you want to keep. Use COBRA only as a short bridge into the January 1 through March 31 window.
Medicare Savings Programs and State Medicaid Brands in 2026
Medicaid.gov describes Medicare Savings Programs as state programs that pay Part B premiums for people with limited income, and they work year-round without waiting for the General Enrollment Period. Applications go through your state Medicaid agency, which uses different brand names: Medi-Cal in California, MassHealth in Massachusetts, AHCCCS in Arizona, BadgerCare in Wisconsin, and TennCare in Tennessee. For 2026, the qualifying limits sit near 135% of the federal poverty level for the broadest tier, roughly $21,500 for a single person, though each state sets its own asset test. Once you are approved, the state enrolls you in Part B through a buy-in agreement and, in many states, coverage begins earlier than the General Enrollment Period would allow. Anyone paying the full $202.90 Part B premium in 2026 on a fixed income should screen for this before waiting for January. The KFF Medicare analysis also finds that millions of eligible people never apply, leaving the benefit unused.
Frequently Asked Questions
What is the Medicare General Enrollment Period and when does it run?
The Medicare General Enrollment Period (GEP) runs January 1 through March 31 every year. It is for people who missed their 7-month Initial Enrollment Period and do not qualify for a Special Enrollment Period. The 2026 GEP ended March 31, 2026, so the next window is January 1, 2027 through March 31, 2027. Coverage starts the first day of the month after you sign up, so an early January application starts coverage February 1, 2027. Apply at ssa.gov/medicare/sign-up or call 1-800-772-1213.
How do I document that I am eligible to use the General Enrollment Period?
Gather your Social Security number, proof of age, and proof of citizenship or lawful residency. If you claim a Special Enrollment Period instead, submit Form CMS-40B with Form CMS-L564, which your employer completes to prove active group coverage from an employer with 20 or more employees. The GEP itself needs no qualifying event, so Social Security only needs to confirm you are 65 or older and not already enrolled in Part B.
What happens if I miss the General Enrollment Period?
Missing March 31 means waiting for the next January 1 opening, a full year later. During that year you have no Part B, and the late penalty keeps growing because another 12-month period passes. In 2026, each full period adds 10% of the $202.90 standard premium, about $20.29 per month, for as long as you have Part B. Part A is the exception: premium-free Part A can start up to 6 months retroactively, and you can apply for it at any time.
Can I get retroactive Medicare coverage through the General Enrollment Period?
Part B coverage under the GEP is not retroactive. It starts the first day of the month after you enroll, which changed in 2023 from the old July 1 start. Premium-free Part A is different: if you are 65 or older and eligible, Part A can be backdated up to 6 months from your application date, but not earlier than the month you turned 65. Ask Social Security to request the retroactive Part A date when you apply.
What is the difference between COBRA and Medicare enrollment for late enrollees?
COBRA continues your former employer plan at 102% of the full premium, roughly $400 to $900 per month for an individual in 2026, and it lasts 18 to 36 months. Medicare Part B is $202.90 per month in 2026. COBRA does not count as active employer coverage, so it never creates a Part B Special Enrollment Period, and the 10% per year penalty still applies. Medicare also becomes primary for most people at 65, so COBRA may pay second or end early.
What state-specific rules apply to Medicare late enrollment?
Medicare enrollment rules are federal, but state Medicaid agencies run the Medicare Savings Programs that can pay your Part B premium: Medi-Cal in California, MassHealth in Massachusetts, AHCCCS in Arizona, and BadgerCare in Wisconsin. Some states also cover or waive the late penalty through the buy-in. Income limits and asset tests differ by state, so apply through your state Medicaid agency, which accepts applications year-round without waiting for the GEP.
Do I qualify for Medicaid help paying for Medicare after enrolling late?
You may qualify if your income falls near 135% of the 2026 federal poverty level, roughly $21,500 for a single person, and your assets are within your state's limit. Medicaid Medicare Savings Programs can pay the $202.90 Part B premium in 2026, and Extra Help can cap Part D costs. Apply at your state Medicaid agency or through Medicaid.gov. See the Medicaid income limits page for state-by-state thresholds.
