Ask a neighbor in Boise County or Ada County who kept working after 65 what confused them most, and you will hear the same question: do I need Medicare yet? The answer sits in a handful of federal rules. This page explains them in plain English and shows what the wrong timing costs. It is general education, not tax or legal advice.
The Short Version: Key Takeaways
- Employer size sets who pays first. Medicare is secondary to a group health plan only when the employer has at least 20 employees and you have the plan because of current employment (42 CFR 411.172).
- Eligibility starts at 65, and the Part B window is 7 months long: 3 months before, the birthday month and 3 months after (42 CFR 407.14).
- When job coverage ends, you have 8 months to join Part B without a penalty, counted from the end of coverage based on current employment (42 CFR 406.24).
- A late start is permanent. The Part B premium rises 10 percent for each full 12 months you could have enrolled and did not (42 CFR 408.22).
- HSAs and Medicare do not mix. Your contribution limit is zero beginning with the first month you are enrolled in Medicare, including retroactive months (IRS Publication 969).
- The 2027 Part B figures are pending. CMS has not yet published them, so we use the 2026 amounts, labelled as 2026 (CMS).
Still working and not sure if Part B can wait?
Send us your birthday, your employer's size and how you are covered. We tell you plainly whether waiting is likely safe, and what each choice costs.
Call or text 208-350-9933 Send us a messageWho Pays First: Your Employer Plan or Medicare
When you have both an employer plan and Medicare, one of them pays first and the other pays what is left. That order is called "primary" and "secondary," and for people 65 or older it turns on how many people your employer has. Federal rules treat an employer as having 20 or more employees if it had 20 or more for each working day in each of 20 or more calendar weeks in the current or the preceding calendar year (42 CFR 411.170).
| Your situation | Who generally pays first | What it means for Part B |
|---|---|---|
| Employer has 20 or more employees and you have its plan because you are actively working | The employer plan; Medicare is secondary | Many people delay Part B, if the plan is a good fit for them |
| You are the aged spouse of a worker of any age who has that kind of plan | The employer plan; Medicare is secondary | Same rule, applied to the spouse |
| Employer has fewer than 20 employees | Medicare generally pays first | Skipping Part B can leave large bills unpaid |
| You turn down the employer plan | Medicare is primary | The plan may not offer coverage that complements Medicare |
Source: 42 CFR 411.172 and 411.170, Electronic Code of Federal Regulations, current through November 9, 2026, read November 12, 2026.
The 20 employee line applies to people 65 or older. A separate threshold of 100 employees applies to people under 65 who are on Medicare because of a disability (42 CFR 411.100). An employer plan also must give an employee or spouse aged 65 or older the same benefits it gives a younger one (42 CFR 411.170). Ask your benefits office how many employees count, and get the answer in writing.
Which Kinds of Coverage Count
The coverage has to come from current employment status, not just from having once worked somewhere. Under the federal definition you have it if you are actively working as an employee, are the employer or are self-employed, or are not actively working but keep your employment rights and your plan is not COBRA continuation coverage (42 CFR 411.104).
| Kind of coverage | Current employment status? | What to check |
|---|---|---|
| Plan from a job you are actively working | Yes | The employer's size and whether you are enrolled in the plan |
| Plan from your spouse's active job | Yes, for a spouse covered through current employment | Your spouse's employer size and your own birthday |
| Self-employed with a group health plan | Only if earnings meet a set test in the prior tax year (42 CFR 411.104(d)) | Bring your tax return to the conversation |
| COBRA continuation coverage | No, for someone who is not actively working | Do not let Part B wait on COBRA |
| Retiree coverage from a past employer | Generally no | Confirm with the plan administrator, in writing |
| Coverage you buy yourself, such as an individual plan | No, it is not employer group coverage | The Part B window may still be running |
Source: 42 CFR 411.104, current employment status and 407.20, current through November 9, 2026. The last two rows apply the regulation's definitions to common situations; we have not found a federal listing by plan type, so confirm with the plan.
Part B Timing at 65 and After
Eligibility for Part B starts when you turn 65 if you are a U.S. resident and a citizen or a long-term lawful resident (42 CFR 407.10). Your initial enrollment period is 7 months: it begins 3 months before the month you first become eligible and ends 3 months after it (42 CFR 407.14).
| When you enroll | When Part B coverage begins |
|---|---|
| In the first 3 months of your initial enrollment period | The first month you are eligible (your birthday month) |
| In the last 4 months of your initial enrollment period | The month after the month you enroll |
| During the general enrollment period (January through March) | The first day of the month after you enroll |
| During a special enrollment period | Under the special enrollment period rules in 42 CFR 406.24 |
Source: 42 CFR 407.25 and 407.15, current through November 9, 2026, read November 12, 2026.
Part A works differently. If you receive Social Security at 65, or start it after 65, you do not file a separate application for hospital insurance (42 CFR 406.6). People who become entitled to Part A are also automatically enrolled in Part B unless they decline within the time the notice allows (42 CFR 407.17). So a person who claims Social Security at 66 while on an employer plan may find a Part B premium coming out of their benefit unless they act on that notice.
The 8 Month Special Enrollment Period
People who delay Part B because of a job-based plan get a special enrollment period. It runs while you are covered by the employer plan and for 8 months after. Technically, it ends on the last day of the eighth consecutive month in which you are at no time enrolled in an employer group health plan based on current employment (42 CFR 406.24).
| Condition | What it means in practice |
|---|---|
| You are eligible for Part B because of age | You are 65 or older and meet the residency and citizenship rules |
| When first eligible, you had employer coverage based on your or your spouse's current employment | Or you enrolled in Part B during your initial enrollment period |
| You kept that coverage, or Part B, every month after | A gap with neither one can cost you the special enrollment period |
| You enroll within the window | Through the last day of the eighth month after employer coverage ends |
Source: 42 CFR 407.20 and 406.24, current through November 9, 2026, read November 12, 2026.
Two warnings follow. The clock is tied to the end of coverage based on current employment, so months of COBRA after you stop work do not extend it. And if you fail to enroll during a special enrollment period you generally lose the right to additional ones. Near retirement, call us before your last day of work.
What a Late Part B or Part D Start Costs
If you do not qualify for a special enrollment period and you miss your initial window, you can sign up during the general enrollment period, January through March, and your Part B premium is increased by 10 percent for each full 12 months you could have been enrolled and were not (42 CFR 408.22). The 2026 standard Part B premium is $202.90 a month and the Part B deductible is $283 (CMS 2026 fact sheet).
| Time you could have enrolled and did not | Penalty rate | Added each month | Added each year |
|---|---|---|---|
| 1 full year | 10% | $20.29 | $243.48 |
| 2 full years | 20% | $40.58 | $486.96 |
| 3 full years | 30% | $60.87 | $730.44 |
| 4 full years | 40% | $81.16 | $973.92 |
| 5 full years | 50% | $101.45 | $1,217.40 |
Source: our arithmetic from 42 CFR 408.22 and the CMS 2026 Part B premium; CMS has not published the 2027 premium, so 2027 amounts will differ.
Extra Part B premium each month, by years of delay (2026 premium)
Source: our arithmetic from 42 CFR 408.22 and the CMS 2026 standard Part B premium of $202.90. The data table above lists the same figures.
The Part D penalty works on a different clock. It applies if there is a continuous period of 63 days or longer after your initial enrollment period when you were eligible for Part D, had no creditable prescription drug coverage and were not in a Part D plan (42 CFR 423.46). It is the greater of an amount CMS sets or 1 percent of the base beneficiary premium for each uncovered month (42 CFR 423.286). If your employer plan has drug coverage, ask whether it is creditable, in writing.
Worried you may already be late?
Tell us your birthday and your coverage history. We check whether a special enrollment period or the general enrollment period applies and what the premium would be.
Call or text 208-350-9933 Send us a messageHSA Contributions and Medicare
This is the trap that catches careful planners. IRS Publication 969 says that beginning with the first month you are enrolled in Medicare, your HSA contribution limit is zero, and the rule applies to months of retroactive coverage (IRS Publication 969). Part A can be backdated: an application filed within 6 months after the first month of eligibility reaches back to that month, and a later one reaches back to the sixth month before the month of filing (42 CFR 406.6(d)). The 2026 limits are $4,400 for self-only coverage and $8,750 for family coverage, plus $1,000 for people 55 or older (IRS Publication 969).
| Medicare coverage starts | Months of HSA eligibility in 2026 | Prorated limit (limit plus $1,000) |
|---|---|---|
| January 1 | 0 | $0 |
| April 1 | 3 | $1,350 |
| July 1 | 6 | $2,700 |
| October 1 | 9 | $4,050 |
Source: our arithmetic using the proration method in IRS Publication 969 (2025 edition, which lists the 2026 limits): ($4,400 + $1,000) times months of eligibility divided by 12. Illustration only; it is not tax advice, so confirm your figures with a tax professional.
The practical lesson: decide on the HSA before you apply for Medicare or Social Security. Some people stop contributions 6 months before they plan to apply; others delay Medicare while the employer plan is primary. We are not tax advisors, so we map the Medicare dates and hand them to your tax professional.
How Many Idahoans Work Past 65
You are not unusual. In the Census Bureau's 2019 to 2023 American Community Survey estimates, about 22.8 percent of Idahoans aged 65 to 74 and 6.4 percent of those 75 and over were employed (Census Bureau, Table S2301). Applying those ratios to the population counts, we estimate roughly 51,765 Idahoans 65 or older were working (our arithmetic, not a published count).
| Area | Age group | People | Labor force participation | Employed share |
|---|---|---|---|---|
| Idaho | 65 to 74 | 192,952 | 23.6% | 22.8% |
| Idaho | 75 and over | 121,439 | 6.6% | 6.4% |
| Ada County | 65 to 74 | 49,133 | 23.9% | 23.2% |
| Ada County | 75 and over | 30,843 | 7% | 7% |
| Boise County | 65 to 74 | 1,498 | 24.2% | 24.2% |
| Boise County | 75 and over | 699 | 1.4% | 1.4% |
Source: U.S. Census Bureau, American Community Survey 2023 5-year estimates, Subject Table S2301, pulled November 12, 2026. "People" means the table's population 16 and over in the age group; "employed share" is the employment to population ratio. Boise County's small population means larger sampling error.
Share of people who are employed, by age group and area, ACS 2019 to 2023
Source: U.S. Census Bureau, ACS 2023 5-year Subject Table S2301. The data table above lists the same figures.
Medigap, Medicare Advantage and Part D Timing
Once you start Part B, three more clocks begin. The supplement window matters most, because it is the only one with a legal guarantee on price and acceptance.
| Choice | Window | Why it matters |
|---|---|---|
| Medigap (Medicare Supplement) | 6 months starting with the first month you are 65 or older and enrolled in Part B | A company may not deny you or charge more because of your health during the window |
| Part D drug plan | Initial enrollment period, then a penalty if there are 63 days or more with no creditable coverage | The penalty adds to your premium and does not go away |
| Medicare Advantage | Your initial enrollment period, then October 15 to December 7 each year | Replaces Original Medicare and may include drug coverage; networks matter |
Source: 42 U.S.C. 1395ss(s)(2)(A) (Medigap guaranteed issue; U.S. Code text via Cornell Legal Information Institute) and 42 CFR 423.46 (Part D penalty), read November 12, 2026.
Idaho adds Medigap protections, covered in our answer on the Idaho Medicare birthday rule and on our Medicare Supplement page. If you start Part B later, your Medigap window starts later too.
Ready to line up Part B, Medigap and Part D dates?
We build the whole timeline with you and price the 2027 plans we represent against your doctors and prescriptions. Our help costs you nothing.
Call or text 208-350-9933 Send us a messageWatch: Understanding Medicare and Working Past 65
If you would rather watch than read, our Medicare Resources page hosts a video called "Understanding Medicare and Working Past Age 65." It covers employer size, HSA timing and what to do when you retire.
After the video, complete the survey so we know your doctors and prescriptions, then we meet by Zoom or phone. In-person meetings take place only at our Idaho City office, by appointment.
A Working Past 65 Checklist
| Question | Why it matters | Where to get the answer |
|---|---|---|
| How many employees does my employer have? | 20 or more makes the employer plan primary | Your benefits office, in writing |
| Is my coverage based on my current job or my spouse's? | Only current employment coverage supports delaying Part B | The plan documents and 42 CFR 411.104 |
| Do I have, or want, an HSA? | Medicare ends the contribution limit | A tax professional and IRS Publication 969 |
| Am I about to claim Social Security? | It can trigger automatic Part A and Part B | The notice from Social Security, within its deadline |
Source: Personal Touch's checklist, built from 42 CFR 411.172, 406.24, 423.46 and IRS Publication 969; not a government list.
Our turning 65 checklist, our guide to Medicare enrollment periods and our answers on working at 65 and missing an enrollment window go deeper on each step.
What to Watch for in 2027
- The 2027 Part B premium and deductible. CMS publishes them in mid-November. We use the 2026 figures ($202.90 and $283) until then, and will refresh this page when the 2027 figures arrive.
- A job change or retirement date. Any change to your coverage starts or stops a clock, so tell us before it happens.
How We Built This Page
Every rule on this page comes from the Electronic Code of Federal Regulations, title 42, as current through November 9, 2026, from CMS's 2026 premiums and deductibles fact sheet, from IRS Publication 969 or from the U.S. Code. The employment figures come from the Census Bureau's ACS 2019 to 2023 five-year Subject Table S2301, pulled November 12, 2026.
Limits: this page is not tax or legal advice, and it does not cover railroad retirement, federal employee or military coverage, or people on Medicare because of disability or end stage renal disease. We have not seen your plan documents. Personal Touch Ins. & Benefits, LLC is an independent agency, and we are glad to talk through your own dates.
Want your own working past 65 timeline, in writing?
Tell us your birthday, your employer's size, how you are covered and whether you have an HSA. We map your Part A, Part B and Part D dates, show the cost of each option and meet by Zoom, phone or in Idaho City by appointment.
Call or text 208-350-9933 Send us a messageFrequently Asked Questions
Do I need Medicare Part B if I am still working at 65 in Idaho?
It depends on your coverage. If you work for an employer with 20 or more employees and you are covered by its group health plan because you are actively working, that plan generally pays first and many people delay Part B. With a smaller employer, Medicare generally pays first, so skipping Part B can leave large bills unpaid. Part A is a separate question, and it is usually premium free. Check your situation with us before you decide.
How long do I have to sign up for Part B after my employer coverage ends?
The special enrollment period for Part B lasts through the last day of the eighth consecutive month in which you are not covered by an employer group plan based on current employment (42 CFR 406.24). There is no late penalty when you enroll inside it. COBRA and retiree coverage generally do not count as current employment coverage, so call us at 208-350-9933 before your last day of work.
What is the Part B late enrollment penalty?
The standard Part B premium is increased by 10 percent for each full 12 months you could have enrolled and did not (42 CFR 408.22). Using the 2026 standard premium of $202.90, one full year late adds about $20.29 a month and two years adds about $40.58, and the added amount continues for as long as you have Part B. We check which window applies to you at no cost.
Can I keep contributing to my HSA after I turn 65 and work past 65?
Not once any part of Medicare begins. IRS Publication 969 says your contribution limit is zero beginning with the first month you are enrolled in Medicare, including months of retroactive coverage. Part A can be backdated up to 6 months, so we map your Medicare dates for you and suggest you share them with a tax professional before you apply for Social Security or Medicare.
Does my spouse need Medicare if I am still working past 65?
Each person has their own Medicare timing. A spouse who is 65 or older and covered through your current employer group plan is treated under the same 20 employee rule as you are (42 CFR 411.172). Tell us both birthdays and how each of you is covered, and we map out both timelines.
What happens to my Medigap or Part D choices when I finally enroll?
A Medigap policy comes with a 6 month window that starts when you are 65 or older and enrolled in Part B, during which a company cannot turn you down or charge more for your health (42 U.S.C. 1395ss(s)(2)(A)). For Part D, a penalty can apply if you go 63 days or longer without creditable drug coverage or a Part D plan after your initial enrollment period (42 CFR 423.46). We time both with you.
Keep Reading
Sources
- 42 CFR 411.172, Medicare benefits secondary to group health plan benefits (aged), accessed November 12, 2026
- 42 CFR 411.170 and 411.100, employers of 20 or more employees and the secondary payer rules, accessed November 12, 2026
- 42 CFR 411.104, current employment status, accessed November 12, 2026
- 42 CFR 407.20 and 406.24, special enrollment period for group health plan coverage, accessed November 12, 2026
- 42 CFR 407.14, 407.15 and 407.25, Part B enrollment periods and start dates, accessed November 12, 2026
- 42 CFR 408.22, increased Part B premiums for late enrollment, accessed November 12, 2026
- 42 CFR 406.6, application and enrollment for hospital insurance (Part A), accessed November 12, 2026
- 42 CFR 423.46 and 423.286, Part D late enrollment penalty, accessed November 12, 2026
- CMS, 2026 Medicare Parts A and B premiums and deductibles fact sheet, accessed November 12, 2026
- IRS Publication 969, Health Savings Accounts and other tax-favored health plans, accessed November 12, 2026
- U.S. Census Bureau, ACS 2023 5-year Subject Table S2301, employment status, accessed November 12, 2026
- 42 U.S.C. 1395ss(s)(2)(A), Medigap guaranteed issue period, accessed November 12, 2026
Figures are labelled with the year they apply to and were checked against the official sources above on the date shown. This page is general education, not individual advice. Personal Touch Ins. & Benefits, LLC is not connected with or endorsed by the U.S. government or the federal Medicare program.