Medicare for Self-Employed Business Owners (2026)

For W-2 employees, Medicare enrollment is simple: HR explains it at 65. For business owners, it's a minefield — an HSA trap that creates taxable excess contributions, IRMAA surcharges triggered by the year you sell your business, and premium deduction rules that differ by entity structure. Here's what to know before you turn 65.

Medicare basics: the four parts

The #1 trap for business owners: HSA and the 6-month lookback

Here's how it plays out: You turn 65 in April but plan to keep working. You figure you'll enroll in Medicare "when you retire" and keep contributing to your HSA. In October (month of your 65th birthday + 6 months), you finally apply for Social Security and Medicare. The SSA automatically retroactively enrolls you in Medicare Part A back to April 1 — your 65th birthday month.

Every HSA contribution you made from April through September is now an excess contribution. The IRS doesn't care that you didn't know Part A started in April — the 6% excise tax (IRC §4973) applies for every year the excess remains in the account.

The 6-month rule in plain terms

• Medicare Part A is retroactive up to 6 months when you enroll late (but never before your 65th birthday).
• Once Part A is effective, HSA eligibility ends — even if you haven't enrolled in Part B yet.
• Result: you must stop HSA contributions at least 6 months before your planned Medicare enrollment date, not on the enrollment date itself.
• If you enroll in Medicare at exactly age 65 (first month of your Initial Enrollment Period), no retroactive period applies — Part A is effective the first of your birthday month and you can contribute pro-rata for the months you were eligible that year.

How to fix excess contributions

If you contributed to an HSA after Part A became effective, you can avoid the 6% excise tax by withdrawing the excess contributions (plus earnings) by your tax-filing deadline including extensions (usually October 15). The earnings are taxable ordinary income in the year withdrawn.²

Initial Enrollment Period: the 7-month window

When you turn 65, you have a 7-month Initial Enrollment Period (IEP): the 3 months before your birthday month, your birthday month, and the 3 months after. Missing this window without a qualifying reason for delay means paying a Part B late enrollment penalty of 10% per 12-month period missed — for life.

When you can delay Part B without penalty

You can delay Part B without penalty if you (or your spouse) are actively working and covered by an employer group health plan from a current employer with 20+ employees. Self-employed owners are not covered by employer coverage — working independently doesn't count as employer-sponsored coverage. Your individual health plan (ACA Marketplace, HDHP, etc.) is not group employer coverage.

Part A enrollment decision

Part A is free for most people (40+ quarters of covered earnings). There's no premium to weigh, so most people enroll in Part A at 65 even if they delay Part B. Exception: if you are still contributing to an HSA and don't want to trigger the 6-month lookback, you may choose to delay both Part A and Part B and wait until you want to stop HSA contributions. Once you want to stop HSA contributions — enroll 6 months after your last planned contribution month.

IRMAA: the income cliff that hits business owners hardest

IRMAA (Income-Related Monthly Adjustment Amount) adds a surcharge to your Part B and Part D premiums based on your MAGI from two years ago. In 2026, your premium is based on your 2024 tax return.

Business owners face two IRMAA surprises that W-2 employees rarely encounter:

1. Business sale spike. You sell your business at age 63 and recognize $2M in gains. Two years later, at 65, you're enrolled in Medicare — and that year's IRMAA is based on the sale year's income. You could owe $649.20/month per person instead of $202.90 for potentially two years while the sale income clears the lookback window.
2. Roth conversion year. You do a large Roth conversion the year you retire (which is a great tax strategy), but if that pushes 2-year-ago MAGI above an IRMAA threshold, you'll pay higher Medicare premiums during those years.

2026 IRMAA brackets: Part B monthly premium

The thresholds below use your 2024 MAGI (modified adjusted gross income). For most business owners, MAGI ≈ AGI + tax-exempt interest + non-taxable Social Security.

Source: CMS 2026 Part B premium announcement (November 14, 2025). MFJ thresholds apply per enrollee — both spouses pay their individual Part B premium.

2026 Part D IRMAA surcharges

Part D surcharges are added on top of your plan's regular Part D premium. Same income thresholds as Part B IRMAA.

Source: CMS 2026 Medicare Part D IRMAA announcement. Verify exact amounts at cms.gov. // Source: CMS 2026 IRMAA per https://www.cms.gov/newsroom/fact-sheets/2026-medicare-parts-b-premiums-deductibles

IRMAA calculator: estimate your 2026 Medicare cost

IRMAA income management strategies for business owners

Unlike retirees drawing from a fixed portfolio, business owners often have meaningful control over the income that appears on their MAGI. The strategies below work best when planned two years before Medicare enrollment — which is age 63 if you plan to enroll at 65.

Strategy 1: Accelerate income before the lookback window

If you know you're selling the business or doing a large Roth conversion, do it in the year before the two-year lookback reaches Medicare. For someone enrolling in Medicare at 66 (January 2026), the lookback year is 2024. A business sale closed in 2021 at age 63 would not affect 2026 IRMAA — but a sale in 2024 would affect 2026 premiums, and in 2025 would affect 2027 premiums.

Strategy 2: File a IRMAA life-change appeal (SSA Form SSA-44)

If your income two years ago was unusually high due to a one-time event (business sale, Roth conversion, distribution), you can appeal to have IRMAA recalculated using a more recent year's income. Qualifying life-changing events include stopping work or reducing hours, the death of a spouse, divorce, and loss of income-producing property. A business sale is not a qualifying life-changing event under current SSA rules — but if it ended your income, "stopping work" may qualify.³

Strategy 3: Reduce MAGI with retirement contributions

In the two years before Medicare enrollment, maximizing deductible retirement contributions directly reduces MAGI. At age 63–64, the super catch-up provision (ages 60–63 under SECURE 2.0 §117) lets you contribute $11,250 as the employee catch-up amount — the highest catch-up available — plus the regular employer contribution up to $72,000 total in a solo 401(k). A business owner at age 63 netting $250K can potentially reduce MAGI by $60,000–$100,000 via retirement plan contributions, potentially staying below an IRMAA threshold entirely.

Strategy 4: Manage Roth conversions around IRMAA cliffs

Roth conversions count toward MAGI for IRMAA purposes. The year before Medicare starts is a classic Roth conversion opportunity — low income, pre-RMD, pre-Social-Security. But fill the bracket carefully: crossing from $108,000 to $110,000 (single) adds $972/year in Part B premiums alone. Model conversions to stop just below each IRMAA cliff.⁴

Deducting Medicare premiums: how the self-employed rules work

Sole proprietors and single-member LLCs

If you are self-employed (no S-corp election), you can deduct 100% of Medicare Part B and D premiums, plus any supplemental (Medigap) premiums, under IRC §162(l) — the self-employed health insurance deduction. This is an above-the-line deduction that reduces AGI, which in turn reduces your MAGI for IRMAA purposes the following year.⁵

The deduction is limited to your business's net profit — you can't deduct more in premiums than you earned. For retired business owners with no active SE income, this deduction disappears.

S-corp owner-employees (more than 2% shareholder)

For S-corp owners, Medicare premiums must be handled carefully to be deductible:

1. The S-corp pays or reimburses the Medicare premiums.
2. The premiums are included in Box 1 (wages) of your W-2 — treated as additional compensation, not a tax-free benefit.
3. The W-2 amount is then deducted on Schedule 1 line 17 as self-employed health insurance under §162(l).

If the premiums are NOT run through payroll and included on the W-2, the §162(l) deduction is lost and the premiums are paid with after-tax dollars.⁵ The net result — with correct setup — is the same as a sole proprietor: above-the-line deduction, FICA not applicable (Medicare premiums are not subject to FICA even when included in W-2 Box 1).

Medicare and HSA in retirement: the "bank receipts" strategy

Once enrolled in Medicare you can no longer contribute to an HSA — but you can spend your existing HSA balance tax-free on Medicare premiums (Part B, D, Medicare Advantage), dental, vision, and qualified medical expenses. You cannot pay Medigap/supplement premiums from your HSA tax-free (Medicare supplement is not a qualifying expense).

The "bank receipts" strategy: for years before Medicare enrollment, don't spend your HSA on current medical bills — pay out of pocket and hold the receipts. The IRS has no deadline for HSA reimbursements. Once you're in Medicare and no longer accumulating new contributions, your large HSA balance reimburses all those prior years' out-of-pocket costs tax-free. This converts after-tax medical spending into tax-free HSA spending retroactively.

Sources

1. CMS — 2026 Medicare Parts A & B Premiums and Deductibles. Announced November 14, 2025. Part B standard premium $202.90/month; Part A hospital deductible $1,736; Part A premium for fewer than 30 quarters $565/month. IRMAA Part B premium range $284.10–$689.90.
2. IRS Publication 969 — Health Savings Accounts and Other Tax-Favored Health Plans. HSA eligibility rules and Medicare disqualification; IRC §223(b)(8) testing period and the 6-month retroactive Medicare Part A rule. Excess contribution rules under IRC §4973.
3. SSA Form SSA-44 — Medicare Income-Related Monthly Adjustment Amount — Life-Changing Event. Documents qualifying life-changing events for IRMAA recalculation using more recent income year.
4. Kiplinger — Medicare Premiums 2026: IRMAA Brackets and Surcharges for Parts B and D. Full 2026 IRMAA bracket table for Part B and Part D; planning strategies.
5. IRC §162(l) — Self-Employed Health Insurance Deduction. Self-employed health insurance deduction applicable to Medicare premiums. S-corp owner-employee W-2 inclusion and §162(l) deductibility requirements per IRS Notice 2008-1 / Rev. Rul. 91-26.

Medicare values verified against CMS 2026 official announcement (November 14, 2025). IRMAA brackets verified against CMS fact sheet and Kiplinger 2026 IRMAA guide. HSA 6-month lookback rule per IRS Publication 969 and IRC §223(b)(8). Updated 2026-06-01. Consult a financial advisor and tax professional for strategy specific to your situation.