Key takeaways
  • You have about 63 days after losing creditable employer drug coverage to enroll in Part D without penalty.
  • The 8-month Medicare SEP applies to Parts A and B — Part D only gets about 2 months.
  • Keep your creditable-coverage notices; they are your proof if a penalty is ever disputed.

You just retired, got laid off, or your employer's plan changed — and your prescription drug coverage is going with it. What happens to your Part D options? The short answer: you get a brief window to act, and the clock is much shorter than most people expect.

Your Part D clock starts immediately

When you lose creditable employer prescription drug coverage — coverage expected to pay, on average, at least as much as standard Medicare Part D — you qualify for a Special Enrollment Period (SEP) to join a Part D plan. For Part D, that window is about two months: you have roughly 63 days from the date your employer drug coverage ends to get new drug coverage without penalty.

This is the detail that trips people up. Medicare gives you eight months to enroll in Parts A and B after your job or group coverage ends. But drug coverage plays by a different, stricter rule: go 63 consecutive days without Part D or other creditable drug coverage, and you can owe a late-enrollment penalty — a permanent monthly surcharge added to your Part D premium for as long as you have drug coverage. Handle your Part B and Part D enrollments together, right when employer coverage ends.

What the penalty actually costs

The Part D late-enrollment penalty equals 1% of the national base beneficiary premium for every full month you went without creditable coverage, rounded to the nearest 10 cents. The base premium changes each year — for 2026 it is $38.99 — so the penalty recalculates annually even though your number of "penalty months" stays fixed.

Example: a 12-month gap in creditable coverage means a 12% surcharge — about $4.70 per month in 2026 — added to your plan premium, every month, permanently. A 24-month gap is roughly $9.40 per month. It does not go away, even if you switch plans or move to a $0-premium plan.

There is one silver lining: the penalty is waived for anyone who qualifies for Extra Help (the Low-Income Subsidy). If your income is limited, check Extra Help eligibility — it can cover premiums, deductibles, and most copays too.

Your three options after employer coverage ends

  1. Enroll in a stand-alone Part D plan (PDP). This pairs with Original Medicare (Parts A and B). Compare plans on Medicare.gov's Plan Finder using your actual prescription list — premiums, deductibles, and tier structures vary widely between plans.
  2. Join a Medicare Advantage plan with drug coverage (MA-PD). If you are switching from employer coverage to Medicare altogether, an MA-PD bundles medical and drug coverage. Your SEP allows joining a Part D or MA-PD plan.
  3. Continue employer coverage via COBRA — with caution. COBRA can keep your prescriptions covered temporarily, but it does not start a new enrollment window when it ends. Relying on COBRA without tracking the 63-day rule can leave you facing a coverage gap plus the late penalty. If you take COBRA, still enroll in Part D within your SEP window.

One important note: if your employer's drug plan was not creditable, you do not get this protection — the penalty clock may already have been running. That is why the creditable-coverage letter matters.

Keep your creditable-coverage notices

By law, your employer or plan must send you a written notice each year — before October 15 — stating whether your drug coverage is creditable. Keep every one of these letters. They are your proof of creditable coverage if Medicare ever questions your penalty status or your SEP eligibility.

If you cannot find the letter, call your former HR department or benefits administrator and request a copy before you enroll in Part D. A plan can also ask you to attest to prior creditable coverage, and documentation makes that painless.

Enrolling: what to have ready

You can enroll in a Part D plan directly with a plan carrier or through Medicare.gov. Have these on hand:

Because plan formularies differ — the same drug can sit on Tier 2 in one plan and Tier 4 in another — enter your exact medications when comparing. A plan with a low premium but poor formulary match for your drugs can cost far more over the year.

Timing traps to avoid

Bottom line: Losing employer drug coverage gives you about 63 days to enroll in Part D penalty-free — act in the same week your coverage ends, confirm the new coverage is creditable in writing, and compare plans using your real prescription list.