Updated: March 12, 2026
Advertising & Editorial Disclosure
Employer coverage from a company with 20 or more employees lets you delay Medicare Part B without a late enrollment penalty.
COBRA and Marketplace plans don't qualify for delayed Medicare enrollment, so missing your Initial Enrollment Period means permanent penalties.
Part B's late enrollment penalty adds 10% to your $203 monthly premium for each year you delay without qualifying coverage.
Most people get Medicare Part A for free after 40 quarters of payroll taxes, even while keeping active employer coverage.
Medicare is the federal health insurance program for U.S. citizens and qualifying residents who are 65 or older, or younger people with certain disabilities, end-stage renal disease or ALS.
It has four parts: Part A covers hospital and skilled nursing care, Part B covers doctor visits and outpatient services, Part C (Medicare Advantage) bundles both through private insurers and Part D covers prescription drugs. Medicare Supplement plans fill the gaps Original Medicare leaves.
Private health insurance covers medical costs through plans purchased from employers or the Health Insurance Marketplace.
At 65, your coverage type determines your Medicare enrollment options. Employer-sponsored plans (yours or a working spouse's), Marketplace plans through HealthCare.gov, COBRA continuation coverage and retiree coverage from a former employer are the four types most relevant to Medicare enrollment decisions. Each has different rules about when you can delay, which parts you must add and what penalties apply.
Active group health plan coverage through your own employer or a working spouse's employer with 20 or more employees lets you delay Medicare Part B without penalty. That employer plan pays first and Medicare is secondary in that arrangement. An 8-month Special Enrollment Period applies after employment or that employer coverage ends, with no penalty, per SSA.gov.
Employer plan (20+ employees) | Yes, though most enroll for free | Yes, no penalty | Yes, if plan is creditable |
Employer plan (under 20 employees) | No | No | Yes, if plan is creditable |
Spouse's employer plan (20+ employees) | Yes, though most enroll for free | Yes, no penalty | Yes, if plan is creditable |
Marketplace/ACA plan | No | No | No |
COBRA | No | No | Depends on plan's creditable status |
Retiree coverage | Verify with benefits administrator | Verify with benefits administrator | Depends on plan's creditable status |
Medicare Supplement plan costs average $189 monthly at age 65, per MoneyGeek's analysis. The 6-month guaranteed issue window opens when you first enroll in Part B. After it closes, insurers in most states can charge more or deny your application based on health history.
Three private insurance scenarios require you to enroll in Medicare at 65 without delay. Marketplace plans, small employer coverage and COBRA all fail to qualify as group health plan coverage for Medicare enrollment purposes. In each case, missing your Initial Enrollment Period triggers permanent late enrollment penalties. Those surcharges differ by part, but all are lifelong additions to your monthly premium.
Medicare becomes the primary payer when you turn 65. Your ACA premium tax credits end the month Part A coverage begins. Enroll at 65 and notify HealthCare.gov when Part A starts to avoid repaying those credits at tax time.
If your employer has fewer than 20 employees, Medicare is the primary payer by law. Your employer plan may refuse to pay claims Medicare would have covered if you don't enroll in Part B on time.
COBRA doesn't count as qualifying employer coverage for Medicare enrollment. Enrolling in COBRA after leaving a job doesn't create or extend a Special Enrollment Period. Missing your Initial Enrollment Period while on COBRA means permanent penalties apply when you eventually enroll.
Medicare's late enrollment penalties are permanent. Not reversible. Medicare adds these penalties to your monthly premium for as long as you have that coverage type, which for most people means for life. The penalty grows with every year you delay past your Initial Enrollment Period without qualifying coverage. Per medicare.gov, the 2026 Part B standard monthly premium is $202.90 before any penalties apply. Missing two full years without qualifying coverage adds $40.58 monthly to that figure, permanently.
Part A | +10% per year not enrolled | Twice the years delayed | $565/month | Only those who pay a Part A premium |
Part B | +10% per full 12-month period without qualifying coverage | Lifetime | $202.90/month | Anyone who misses the IEP without qualifying coverage |
Part D | +1% of the $39 national base per month without creditable drug coverage | Lifetime | Varies by plan | Anyone who goes 63+ days without creditable coverage after first eligible |
Part D's penalty works differently than Part B's. It's recalculated each year because the national base beneficiary premium changes annually. Creditable drug coverage means your private plan is expected to pay at least as much as standard Medicare Part D on average. Your plan administrator is required to notify you each year whether your current coverage meets that standard.
Medicare has three enrollment periods. The Initial Enrollment Period (IEP) is a 7-month window starting 3 months before the month you turn 65. The Special Enrollment Period (SEP) gives you 8 months to sign up after active employer coverage ends. COBRA and retiree coverage don't open a Special Enrollment Period. The General Enrollment Period (GEP) runs January 1 through March 31 each year. Coverage starts the month after you enroll during the GEP, and late enrollment penalties apply.
Yes, you can have both. When you do, coordination of benefits rules determine which plan pays first (the primary payer) and which pays second (the secondary payer). The primary payer processes the claim first; the secondary payer covers some or all of what remains. Who pays first depends on your insurance type, your employer's size and whether you or your spouse are actively working.
Active employer (20+ employees) | Employer plan | Medicare |
Active employer (under 20 employees) | Medicare | Employer plan |
Spouse's active employer (20+ employees) | Employer plan | Medicare |
Marketplace plan + Medicare | Medicare | Marketplace plan (no ACA subsidy) |
Retiree coverage + Medicare | Medicare | Retiree plan |
COBRA + Medicare | Medicare | COBRA |
If you have both Medicare and a Marketplace plan, your ACA premium tax credits end the month Part A begins. Medicare becomes the primary payer and you pay the full Marketplace premium with no financial assistance. For most people turning 65, dropping the Marketplace plan and adding a Medicare Advantage plan is the more cost-effective path once you understand what Medicare doesn't cover and your actual out-of-pocket exposure.
Delaying Medicare is legally permitted with qualifying employer coverage, but it requires verification before your 65th birthday. A wrong assumption, like believing COBRA counts toward an enrollment delay, can result in permanent monthly surcharges. These five steps confirm your eligibility, protect against coverage gaps and help you avoid a lifelong financial mistake.
If your company has fewer than 20 employees, Medicare is the primary payer by law. Skipping Part B creates coverage gaps, since your employer plan may refuse claims Medicare would have covered.
Ask your benefits administrator whether your current drug coverage meets Medicare's creditable standard. If it doesn't, you'll owe a Part D penalty starting from your first eligibility date, added to your premium for life.
Your ACA premium tax credits end the month Part A coverage starts. Reporting this change promptly to HealthCare.gov prevents repaying those credits at tax time. The IRS requires this adjustment when Medicare eligibility begins, so act as soon as you have a confirmed Part A start date.
Review how to sign up for Medicare to confirm exactly when your coverage starts before ending any existing plan. Even a short gap affects how your insurer processes claims. A day without coverage can create billing disputes between plans that take months to resolve.
SHIP counselors provide free, unbiased Medicare enrollment help with no sales agenda. These programs operate in all 50 states and are funded by the federal government to guide Medicare beneficiaries. Find your local SHIP at medicare.gov before making any enrollment decision.
Whether you delay Medicare or enroll at 65 comes down to one factor: your coverage type. Active employer coverage from a company with 20 or more employees earns a penalty-free delay. COBRA and Marketplace plans don't. Missing the wrong deadline adds a permanent surcharge to your $202.90 monthly Part B premium. Get the distinction right before your 65th birthday.
We've answered the most frequently asked questions about signing up for Medicare when you have private insurance:
Missing your Initial Enrollment Period adds a permanent 10% Part B surcharge per year delayed. At 2026 rates, two years of delay costs an extra $41 monthly for life. Part D adds a separate 1% monthly penalty per month without creditable coverage.
No, once you qualify for Medicare. Federal law prohibits selling Marketplace plans to known Medicare beneficiaries. Exceptions apply if you'd owe a Part A premium or have end-stage renal disease without Medicare enrollment.
Not if your spouse's employer has 20 or more employees. You can delay Part B using the 8-month Special Enrollment Period after coverage ends. With fewer than 20 employees, Medicare is the primary payer and Part B enrollment is required.
Medicare enrollment ends your HSA contribution eligibility. Stop contributions at least 6 months before enrolling, since Part A coverage can be retroactive by up to 6 months. Contributing after enrollment triggers IRS tax penalties.
COBRA doesn't qualify as active employer coverage for Medicare enrollment. It doesn't trigger a Special Enrollment Period. Missing your Initial Enrollment Period while on COBRA means permanent penalties apply when you eventually enroll.
About Mark Fitzpatrick
Mark Fitzpatrick, a Licensed Property and Casualty Insurance Producer, is MoneyGeek's resident Personal Finance Expert. He has analyzed the insurance market for over five years, conducting original research for insurance shoppers. His insights have been featured in CNBC, NBC News and Mashable.
Fitzpatrick holds a master’s degree in economics and international relations from Johns Hopkins University and a bachelor’s degree from Boston College. He's also a five-time Jeopardy champion!
He writes about economics and insurance, breaking down complex topics so people know what they're buying.
