Turning 65 and Still Working? What to Know Before Medicare Open Enrollment

By Joshua Lavine, CEO and Company Culture Expert, Capitol Benefits  ·  Last updated October 23, 2026

If you are turning 65 and still working, whether you can delay Medicare without a penalty comes down to the size of your employer. At a company with 20 or more employees you can usually stay on the group plan and delay Part B penalty free, while at a smaller employer Medicare generally becomes primary, and delaying then costs 10 percent of the Part B premium for every full 12 months you wait, for as long as you have Part B. If you are already on Medicare, the Annual Enrollment Period to change plans for 2027 runs October 15 through December 7, 2026.

Every fall the Medicare ads start running, and every fall the same question lands on HR desks and in our inbox: I am turning 65, or my spouse is, so what do I actually have to do?

The honest answer is that it depends on two things most people never hear about from the ads: where you are in your own enrollment timeline, and how many people work at the company that provides your coverage. Here is how to think about both, whether you are the employee or the employer they ask first.

Two different windows that often get mixed up

The Annual Enrollment Period runs October 15 through December 7, 2026. It is for people who already have Medicare. During those weeks they can switch between Original Medicare and a Medicare Advantage plan, change Medicare Advantage plans, or join, drop or change a Part D prescription drug plan. Changes take effect January 1, 2027.

The Initial Enrollment Period is the first chance to sign up, and it is personal to you. It lasts seven months: the three months before the month you turn 65, your birthday month, and the three months after. If you are turning 65 next spring, your window has nothing to do with the October to December calendar.

So if an employee mentions the fall enrollment ads, the first useful question is whether they are already on Medicare or approaching 65.

Still working at 65? Company size changes the answer

This is the part that surprises people most.

If your employer has 20 or more employees, your group health plan generally stays primary while you are actively working. Many people in that situation keep their employer coverage and delay Part B without a penalty. When the job or the coverage ends, a Special Enrollment Period gives you eight months to sign up for Part B.

If your employer has fewer than 20 employees, Medicare generally becomes the primary payer at 65. That means the group plan may only pay after Medicare, and skipping Part B can leave real gaps. In most small-employer situations, enrolling in Part B on time is the safer path.

Two common traps: COBRA and retiree coverage do not count as coverage based on current employment for this purpose. Someone who leaves a job and moves onto COBRA should not assume they can keep putting Part B off.

What it costs, and what waiting can cost

The standard Part B premium for 2026 is $202.90 a month, with a $283 annual deductible. The Medicare Trustees project about $209.50 a month for 2027, and CMS typically confirms the official figure in the fall. Higher-income households pay more through income-related adjustments.

The bigger number to watch is the penalty. If you go without Part B or other qualifying coverage when you should have enrolled, your Part B premium goes up 10 percent for each full 12-month period you could have had it, for as long as you have Part B. Part D has its own late penalty for going without creditable drug coverage, which is why the employer’s annual Part D creditable coverage notice matters so much.

If you have a health savings account

Once any part of Medicare begins, you can no longer contribute to an HSA. You can still spend the money already in it on qualified expenses.

The detail that catches people: if you sign up for Medicare after 65, Part A coverage can be backdated up to six months, though not earlier than the month you turned 65. Contributions made during that retroactive period can create a tax problem. A good rule of thumb is to stop HSA contributions about six months before you plan to enroll. Applying for Social Security benefits also enrolls you in Part A automatically.

For employers: what to tell an employee turning 65

HR does not need to be a Medicare expert, but a few plain statements go a long way:

1. Tell them whether your company has 20 or more employees, since that drives whether they can delay Part B.
2. Point them to your Part D creditable coverage notice so they know whether your drug coverage counts.
3. If they have an HSA, remind them that contributions stop once Medicare starts.
4. When they leave or retire, give them written confirmation of their coverage dates. They may need it to prove they had employer coverage when they enroll in Part B later.
5. Suggest they talk it through with someone before deciding, rather than going by the ads.

For anyone already on Medicare: a quick review before December 7

Plans change every year. Before the window closes, check whether your doctors and pharmacies are still in network, whether your prescriptions are still covered at the same tier, and what your total out-of-pocket costs would look like next year, not just the monthly premium. If you are in a Medicare Advantage plan and change your mind after January 1, there is a separate Medicare Advantage Open Enrollment Period from January 1 through March 31.

Frequently Asked Questions

When is Medicare open enrollment for 2027 coverage?

The Annual Enrollment Period runs October 15 through December 7, 2026. Changes made during that window take effect January 1, 2027.

I am turning 65 next year. Do I sign up during the fall window?

Not necessarily. Your Initial Enrollment Period is the seven months around your 65th birthday month: three months before, your birthday month and three months after. That is your first chance to enroll.

Can I delay Part B if I am still working?

Usually yes, if you are covered by a group health plan through current employment at an employer with 20 or more employees. At a smaller employer, Medicare generally pays first, so delaying Part B can leave gaps in coverage.

Does COBRA let me delay Part B?

No. COBRA and retiree coverage are not based on current employment, so they do not give you the right to delay Part B without a penalty.

What is the Part B late enrollment penalty?

Your premium increases 10 percent for each full 12-month period you could have had Part B but did not, and the increase lasts as long as you have Part B.

What is the Part B premium for 2027?

The standard 2026 premium is $202.90 a month. The Medicare Trustees project about $209.50 for 2027, and CMS typically announces the official amount in the fall.

When should I stop contributing to my HSA?

Contributions must stop once Medicare coverage begins. Because Part A can be backdated up to six months when you enroll after 65, many people stop contributing about six months before they apply.

Related reading from Capitol Benefits

• Your Medicare Part D Notice and the Stricter 2027 Test, the employer notice that tells employees whether their drug coverage counts
• HSAs for Late Career Employees, where Medicare timing and health savings accounts meet
• Employee Benefits at Capitol Benefits, for employers in DC, Maryland and Northern Virginia