Retiring After 65? From Job Coverage to Medicare in NJ
If you kept working past 65 on a job-based plan, you have an 8-month window to sign up for Part B when that coverage or the job ends. COBRA does not extend it. Here is the order of steps for New Jersey retirees.
Key takeaways
- If your employer has 20 or more employees, its group plan pays first while you work, and you can usually delay Part B without a penalty. With fewer than 20, Medicare pays first.
- When the job or the coverage ends, you have an 8-month Special Enrollment Period to sign up for Part B. It starts when you stop working, even if you take COBRA.
- Miss it and the Part B penalty is 10% for each full 12 months you could have had Part B. Two years late turns $202.90 into $243.50 a month at 2026 rates, for life.
- For drugs, avoid going more than 63 days without creditable coverage, or a Part D penalty applies.
- Your six-month Medigap open enrollment period starts when Part B starts, which is when New Jersey companies must accept you whatever your health.
More New Jersey residents are working past 65 and keeping their employer's health plan. That is often a sensible choice. The risk comes at the end, when the job or the coverage stops and Medicare has to be in place on time.
Get the order of steps right and the move is smooth: no penalty, no gap, and your pick of Medigap plans without health questions. Get it wrong and you can face a lifetime penalty or months without coverage.
Here is the sequence we walk clients through, with the rules from Medicare.gov and the 2026 numbers.
Do I need Part B while I am still working?
It depends on the size of your employer. According to Medicare.gov, if you are 65 or older with group coverage from your own or your spouse's current job and the employer has 20 or more employees, the group plan pays first and Medicare pays second. With fewer than 20 employees, Medicare pays first, so you generally need Part A and Part B in place.
| Your situation | Pays first | What it means for Part B |
|---|---|---|
| Current job, employer with 20 or more employees | The group plan | You can usually delay Part B without a penalty |
| Current job, employer with fewer than 20 employees | Medicare | Sign up for Part B when first eligible |
| Retiree coverage from a former job | Medicare | The retiree plan may require Part A and B |
| COBRA after the job ends | Medicare, once you have it | COBRA does not extend your window |
Source: CMS fact sheet: 2026 Medicare Parts A and B premiums and deductibles.
When do I sign up for Medicare after leaving my job?
Within your 8-month Special Enrollment Period. Medicare.gov says the window starts when you stop working or lose the coverage, even if you choose COBRA or other coverage that is not Medicare. Most people sign up so Part B starts the day after job coverage ends, to avoid a gap.
- Get the end date of your employer coverage in writing from HR or your benefits office.
- Ask for proof of coverage. Social Security uses an employment form to confirm you had group coverage based on current work.
- Apply for Part B with Social Security, choosing a start date that matches the end of job coverage.
- Choose your drug coverage: a Part D plan or a Medicare Advantage plan with drugs, starting the same day.
- Choose Medigap or Medicare Advantage before Part B starts, so there is no gap.
What does it cost if I miss the window?
A Part B penalty for as long as you have Part B. It is 10% of the standard premium for each full 12-month period you could have had Part B but did not (Medicare.gov). At 2026 rates, two years late raises $202.90 to $243.50 a month.
Source: Medicare.gov penalty rule applied to the 2026 standard Part B premium of $202.90.
For drug coverage, Medicare.gov says you avoid the Part D penalty as long as you do not go more than 63 days without creditable drug coverage. Ask your employer for its creditable coverage notice and keep it.
When should I buy a Medigap plan in New Jersey?
Right as Part B starts. Your Medigap open enrollment period is six months long and starts the month you are 65 or older and have Part B (Medicare.gov). The New Jersey Division of Aging Services Medigap chart warns that after your first six months of Part B, a company may turn you down or charge more based on your health.
For a sense of price, the state's June 2026 chart shows Plan G at age 65 from $147.88 to $260.98 a month for women, at preferred rates. Older ages cost more. Our Plan G vs Plan N post has the full table.
Before your last day of work
- Confirm the coverage end date
- Get the employer coverage form signed
- Apply for Part B with the right start date
- Compare Medigap and Medicare Advantage
Do not forget
- Dental and vision usually end with the job
- Your spouse may be on your plan and need their own coverage
- Stop HSA contributions in time
- Keep your creditable coverage letters
The bottom line
If you are working past 65 in New Jersey, confirm whether your employer has 20 or more employees, then plan your Part B start date to begin the day job coverage ends. You have 8 months, COBRA does not extend them, and a late start can add $487 a year or more to your Part B cost for life. Buy Medigap within six months of your Part B start.
Frequently asked questions
Do I have to sign up for Medicare at 65 if I am still working?
Not always. If your employer has 20 or more employees, its group plan pays first and you can usually delay Part B without a penalty. With fewer than 20 employees, Medicare pays first and you generally need Part B.
How long do I have to sign up for Part B after I retire?
You have an 8-month Special Enrollment Period that starts when you stop working or lose the job-based coverage, whichever happens first. Taking COBRA does not extend it.
Is COBRA creditable coverage for Medicare?
COBRA does not extend your window to sign up for Part B. For drugs, ask the plan for its creditable coverage notice, and do not go more than 63 days without creditable drug coverage.
When does my Medigap open enrollment start if I retire after 65?
When your Part B starts. It lasts six months, and during it companies must sell you a Medigap plan whatever your health.
Sources
- Medicare.gov: Working past 65 Centers for Medicare & Medicaid Services
- Medicare.gov: Who pays first? Centers for Medicare & Medicaid Services
- Medicare.gov: Avoid late enrollment penalties Centers for Medicare & Medicaid Services
- CMS fact sheet: 2026 Medicare Parts A and B premiums and deductibles Centers for Medicare & Medicaid Services
- New Jersey Medicare Supplement Policies (Medigap) monthly premium at age 65, female preferred rates, June 2026 New Jersey Department of Human Services, Division of Aging Services
- Medicare.gov: When can I buy Medigap? Centers for Medicare & Medicaid Services
Please note: We do not offer every plan available in your area. Any information we provide is limited to those plans we do offer in your area. Please contact Medicare.gov or 1-800-MEDICARE to get information on all of your options.Garden State Medicare Solutions is not connected with or endorsed by the United States government or the federal Medicare program. Medicare has neither endorsed nor reviewed this information. This article is general information, not medical, tax or legal advice.
