COBRA vs Medicare Assessment Tool

Key takeaway: COBRA is not considered coverage based on current employment, which means choosing it over Medicare at 65 can lock you into permanent Part B and Part D late enrollment penalties that follow you for the rest of your life.

What this helps you decide

• Whether to choose COBRA or Medicare when you leave your job at or after 65 — and why this decision cannot be undone without cost
• How much the Part B and Part D late enrollment penalties add up to in real dollars when COBRA replaces Medicare instead of supplementing it
• Whether using COBRA alongside existing Medicare enrollment is fine (it is) versus using COBRA instead of enrolling in Medicare (it is not)
• How the total monthly cost of COBRA compares to Original Medicare plus a Medigap plan side by side

Who this is for

• Someone who just turned 65 or is approaching 65 and lost their job — and is trying to decide whether to elect COBRA or enroll in Medicare right away
• A person who already took COBRA after leaving a job and is now wondering whether they've put themselves at risk of a penalty
• Anyone who has both Medicare and COBRA active at the same time and wants to understand how the two interact
• A spouse or family member trying to help a loved one avoid a costly, permanent mistake at Medicare enrollment time

Example results

Example 1 — COBRA instead of Medicare for 18 months: permanent penalties on both Part B and Part D. Imagine you turn 65 in January 2026, lose your job, and elect COBRA instead of enrolling in Medicare. Your Initial Enrollment Period closes, and you ride COBRA for the full 18 months it's available. When COBRA ends in July 2027, you finally apply for Medicare. Because COBRA is not creditable coverage for Medicare purposes, you've gone 18 months without enrolling in Part B when you were first eligible. That's one full 12-month period of delay, which triggers a 10% Part B penalty. The 2026 Part B premium is $202.90 per month, so your penalty adds $20.29 to your premium — permanently. Every year. Meanwhile, if you also went 18 months without Part D drug coverage, you owe a Part D penalty of 1% of the base premium ($38.99) for each of those 18 months: 18 x 1% x $38.99 = $7.02 added to your monthly Part D premium — also permanently. In year one alone, those two penalties together cost you an extra $327.72. Over a 20-year retirement, you're looking at more than $6,500 in unnecessary fees, and that figure grows each year as base premiums rise.

Example 2 — Already enrolled in Medicare, then adds COBRA for dental and vision: no penalty. You enrolled in Medicare Part A and Part B right at 65, as required. When you left your job at 66, your employer offered COBRA. Because you're already on Medicare, you can elect COBRA if you want — maybe it covers dental, vision, or other services Medicare doesn't. This is fine. You're not using COBRA to delay Medicare enrollment; you're stacking it on top of coverage you already have. Medicare pays primary (it's your main insurance), and COBRA pays secondary for costs it covers. There's no penalty risk here at all. The key distinction is sequence: Medicare first, then COBRA on top. Not COBRA instead of Medicare.

Example 3 — COBRA vs. Medicare side-by-side cost comparison. Let's look at real monthly numbers. COBRA continues your former employer's group plan, but now you pay both your share and the employer's share plus a 2% administrative fee. A typical COBRA premium for a 65-year-old runs around $600 per month. Over 18 months, that's $10,800 total — and at the end of it, you still face late enrollment penalties. Now compare: Medicare Part B is $202.90 per month, a standalone Part D plan averages $38.99 per month, and a Medigap Plan G (which covers most gaps in Original Medicare) runs approximately $165.85 per month for a 65-year-old. Total: $407.74 per month. That's $192.26 less per month than COBRA — roughly 47% cheaper. Over those same 18 months, you'd spend $7,339.32 instead of $10,800: a savings of $3,460.68. And with the Medicare route, you'd have no penalties at the end of it.

Sample scenarios

Scenario	Input	Result
COBRA instead of Medicare for 18 months	Age 65, left job, chose COBRA, never enrolled in Medicare during that time	Part B penalty: +$20.29/mo permanently. Part D penalty: +$7.02/mo permanently. Total extra cost: $327.72/yr and rising.
COBRA on top of existing Medicare	Already enrolled in Parts A and B; elected COBRA for dental/vision after leaving job	No penalty. COBRA supplements Medicare. Medicare pays primary; COBRA picks up secondary costs it covers.
Monthly cost comparison	COBRA at $600/mo vs. Part B + Part D + Medigap G	COBRA: $600/mo ($10,800 over 18 months, plus penalties). Medicare route: $407.74/mo ($7,339 over 18 months, no penalties). Savings: $3,461.
COBRA ends, then tries to enroll in Part B	COBRA ran 18 months, SEP window missed	Must wait for General Enrollment Period (Jan–Mar). Coverage doesn't start until July. Additional months of delay accumulate more penalty.

What to do next

• If you're approaching 65 and still working, confirm your employer's size (20+ or fewer employees) — this determines whether you can delay Medicare or must enroll immediately to avoid penalties. Don't rely on COBRA either way as a substitute for enrolling.
• If you already elected COBRA instead of enrolling in Medicare and are still within your Initial Enrollment Period or Special Enrollment Period window, enroll in Medicare now. The sooner you enroll, the fewer months of penalty you'll accumulate.
• If your COBRA has already ended, contact Social Security (1-800-772-1213) or your State Health Insurance Assistance Program (SHIP) counselor right away. You may be in a General Enrollment Period gap and need guidance on your exact penalty amount and earliest start date.
• If you want drug coverage or supplemental coverage on top of Medicare, look at standalone Part D plans and Medigap policies rather than COBRA. Run the numbers — in most cases the Medicare route costs less and eliminates penalty risk entirely.

Key facts

• COBRA continuation coverage does not count as coverage based on current employment for Medicare purposes. It does not protect you from Part B or Part D late enrollment penalties, no matter how long it lasts.
• Choosing COBRA instead of enrolling in Medicare when first eligible can result in permanent Part B and Part D late enrollment penalties that increase your premiums for the rest of your life. The Part B penalty is 10% for each full 12-month period you were eligible but not enrolled. The Part D penalty is 1% of $38.99 for each month without creditable drug coverage.
• If you are already enrolled in Medicare, adding COBRA on top of it is perfectly acceptable and carries no penalty risk. The problem arises only when COBRA is used as a substitute for Medicare enrollment, not as a supplement to it.

Related decisions

• Employer coverage vs. Medicare — Understand when your employer plan is primary versus when Medicare takes over, and when delaying Medicare is actually allowed.
• Special Enrollment Period — Learn which life events give you a legitimate penalty-free window to enroll in Medicare after your Initial Enrollment Period closes.
• When should I sign up for Medicare? — Map out the full enrollment timing decision based on your age, employment, and coverage situation.
• Medicare cost scenario planner — Run a full cost comparison across coverage combinations to find the option that fits your budget.