If you think COBRA can take the place of Medicare, you’re setting yourself up for big medical bills. This is one of the biggest mistakes I see people make.
Here’s the truth: Once you’re eligible for Medicare, you must enroll in Part A and Part B — even if you have COBRA. That’s because COBRA is always secondary to Medicare. If you don’t have Medicare in place, COBRA may not pay at all.

The Key Rule: COBRA Is Secondary, Medicare Is Primary
When you turn 65, Medicare is the first line of coverage. COBRA only pays after Medicare. Without Part A and B, it’s as if you’re uninsured. That means denied claims, permanent late-enrollment penalties, and a long wait before coverage kicks in.

Medicare & COBRA Coverage Situations

Why Waiting Can Be Costly
No Special Enrollment Period (SEP) after COBRA ends. Unlike employer insurance, COBRA doesn’t give you a penalty-free window to sign up later. Miss your Initial Enrollment Period and you may wait until January–March to apply, with coverage starting the following month.

Lifetime penalties. For every year you delay Part B, your premium goes up 10% — forever.

Drug coverage confusion. Some COBRA drug plans are creditable, others are not. If it’s not, you’ll also face permanent Part D penalties.

When COBRA Still Helps
In some cases, it makes sense to keep COBRA alongside Medicare — for example, if it offers extra dental or vision benefits. But it should never replace Medicare.

Bottom Line
If you’re turning 65 with COBRA:
✅ Enroll in Medicare Part A & Part B on time.

✅ Confirm if your COBRA drug coverage is creditable.

✅ Use COBRA only as a secondary layer, not your primary insurance.

Getting this wrong can cost you thousands — and the penalties don’t go away.

Helpful Resources
Medicare Rights Center Q&A on COBRA and Part B

Medicare Interactive: COBRA and Medicare Coordination

Center for Medicare Advocacy: COBRA Is Not Coverage as a “Current” Employee