Your Part B sign-up deadline after retiring

The deadline to sign up for Part B after retiring is generally 8 months after the employment or employer group health coverage ends, whichever happens first. This Special Enrollment Period is for people who delayed Part B while covered by a plan based on their own or their spouse's current employment. Medicare.gov explains the deadline and coverage start dates; confirm your own dates with Social Security.

Your Part B sign-up window after retiring

  1. Day 0Your job or your employer coverage ends, whichever comes first
  2. 8 monthsPart B Special Enrollment Period. Sign up any time in this window without a penalty
  3. After the windowLate penalty risk. You may have to wait for the General Enrollment Period, January 1 to March 31, and pay more for as long as you have Part B

The clock starts with whichever ends first. If you stop working but your employer keeps your coverage for a few more months, the window still starts when your job ends.

COBRA and retiree coverage don't extend it

This is the mistake that catches the most people. Medicare.gov says COBRA isn't considered group health plan coverage, so having COBRA doesn't change when your window ends. The same is true of retiree coverage.

Medicare.gov also lists the end of COBRA or retiree coverage as a situation that doesn't qualify for a Special Enrollment Period. If you wait for COBRA to run out, you may already be past your window.

Timing your Part B start

Part B generally starts the first month after you sign up. If you sign up while you or your spouse are still working, or within the first full month after employer coverage ends, Medicare.gov says you can ask to delay your Part B start date by up to 3 months.

The cleanest plan is to sign up a month or two before your retirement date and coordinate a first-of-the-month Part B effective date with the end of job coverage. If the employer plan ends midmonth, ask how to address the potential gap. That avoids both a gap and paying for Part B while you still have employer coverage.

If you already have Part A, you sign up for Part B through Social Security at SSA.gov. Social Security may ask for proof of your employer coverage, so ask your employer for it before you retire.

What the penalty costs

If you miss the window, your Part B premium goes up 10% for each full 12-month period you could have had Part B but didn't. Medicare.gov says the penalty is usually charged for as long as you have Part B, which for most people is life.

The penalty is added to the standard premium, which is $209.50 (projected by the Medicare Trustees; CMS confirms the final figure in November) a month in 2027. See how much Medicare Part B costs.

Your other deadlines when you retire

  • Medigap: your Medigap Open Enrollment Period, which lasts 6 months, starts the first month you have Part B and are 65 or older. It happens once, so start Part B when you're ready to buy Medigap.
  • Medicare Advantage or Part D: you can usually join when you first get Part B. Part D has its own late penalty if you go without creditable drug coverage.
  • Spouses: if your spouse was on your employer plan, check their Medicare and coverage dates too.

See how a Medicare Special Enrollment Period works, how Medicare works with employer or COBRA coverage, and Medicare Parts A, B, C and D explained.

Make a retirement coverage timeline before submitting forms

Write down the last day of current employment, the last day of employer coverage and the requested Medicare start month. These are separate facts. An eight-month enrollment opportunity does not mean you should wait eight months if the employer plan stops paying as primary coverage sooner.

Part B starts on the first of a month. If employer coverage ends in the middle of a month, ask Social Security and the benefits administrator how the dates should be coordinated. Do not assume you can request Part B to begin on any day you choose. Confirm the approved effective date before relying on a replacement policy.

What to collect from your employer

  • Written confirmation of employment and group health coverage dates.
  • The benefits office's instructions for documenting coverage based on current employment.
  • The date medical and prescription benefits end for you and any covered spouse.
  • Any notice describing whether the prescription coverage is creditable for Part D.
  • Information about retiree coverage, COBRA or an HSA that could affect your transition.

If you already have Part A and are applying for Part B, ask Social Security which application and employer-evidence forms are required for your situation. Save submission confirmations and follow up if more information is requested. Social Security handles the enrollment decision; an agent cannot approve Part B or waive a penalty.

Part B, drug coverage and Medigap have different clocks

Confirm the medical coverage start first, then coordinate the health or drug plan you intend to use with Medicare. Do not assume that the Part B eight-month window is also a safe period to go without creditable prescription coverage. Ask for the drug enrollment deadline separately.

Also review any Medigap rights before leaving employer coverage. If you are considering Medicare Advantage, check the doctors, hospitals, prescriptions and plan start date. A spouse who is not yet eligible for Medicare needs a separate coverage solution; your Medicare enrollment does not cover them as a dependent.

Before contributing to an HSA near retirement, obtain guidance about Medicare enrollment and possible retroactive Part A coverage. Coordinate that tax question with your benefits office or qualified tax adviser. Bring the resulting dates to the insurance review so every part of the transition fits together.

Quick questions

How long do I have to sign up for Part B after I retire?

8 months after your job or employer coverage ends, whichever comes first.

Does COBRA give me more time to sign up for Part B?

No. COBRA isn't considered group health plan coverage, so it doesn't change when your window ends.

Can I sign up before I retire?

Yes. You can sign up while still working and ask to delay your Part B start by up to 3 months.

How The Jordan Insurance Agency helps

The Jordan Insurance Agency is an independent agency based in Charlotte, North Carolina. We help you pick a Part B start date that avoids a gap, and we compare Medigap, Medicare Advantage and Part D plans for your doctors and prescriptions.

There is no fee for our help. Carriers pay the agent, so your premium is the same whether you enroll with us or on your own.

Next steps: read how a Medicare Special Enrollment Period works and Medicare Parts A, B, C and D explained.

Part B sign-up rules checked October 17, 2026. Sources: Medicare.gov — When does Medicare coverage start?, Medicare.gov — Avoid late enrollment penalties, AMAC — Medicare costs 2027 (cites 2026 Medicare Trustees Report).