Medicare & IRMAA: the overview
Medicare is the federal health insurance most people join at 65[1]. Two parts of it cost money every month and depend on choices you make: Part B (doctors and outpatient care) and Part D (prescription drugs). In 2026 the standard Part B premium is $202.90 a month[4]. Higher-income beneficiaries pay more through the income-related monthly adjustment amount, IRMAA, which is added to both Part B and Part D[6].
The decisions
- When to enroll. The initial enrollment window runs from three months before the month you turn 65 to three months after it[2]. Signing up late without other qualifying coverage brings penalties that usually last as long as you have the coverage: Part B goes up 10% for each full 12-month period you could have had it, and Part D adds 1% of the national base beneficiary premium ($38.99 in 2026) for each month without creditable drug coverage after a gap of 63 days or more[3].
- How much income to show two years ahead. IRMAA is set from the modified AGI on your tax return from 2 years earlier[6], so a Roth conversion or a large capital gain at 63 shows up in the premiums at 65. For 2026 the surcharge starts above $109,000 on an individual return and $218,000 on a joint return, with the top tier at $500,000 or more (individual) and $750,000 or more (joint)[4]. The first tier adds $81.20 a month to Part B and $14.50 to Part D for each person on Medicare; the top tier adds $487.00 and $91.00[4]. The tiers are cliffs: one dollar over a threshold puts you in the whole tier.
- Whether to appeal. If your income has dropped since that older tax year because of a life-changing event (stopping or cutting back work, marriage, divorce, a spouse’s death, or the loss of a pension, among others), you can ask Social Security to use a more recent year[7]. The request is made on form SSA-44[6].
- What to do with an HSA. From the first month you are enrolled in Medicare, your HSA contribution limit is zero[8], though money already in the account can still be spent. Before then, the 2026 limits are $4,400 for self-only and $8,750 for family coverage[9].
What to read, in order
Start with how the IRMAA lookback works. If you will still be working at 65, read Medicare while working next, and use the late-enrollment penalty calculator to see what a delay costs. Appealing IRMAA covers the SSA-44 form, and the HSA article covers the account’s tax treatment and what happens when it is inherited. The full tier tables are on the 2026 IRMAA tiers page. IRMAA counts a different income from the ACA and the tax return; see the many MAGIs for how they differ, and cliff margins for how much room to leave below a threshold.
Start here
- IRMAA: the Medicare surcharge with a two-year memoryMedicare premiums are set by your income from two years earlier. The 2026 tiers, why the boundaries are cliffs, and how a Roth conversion at 63 raises premiums at 65.
- Working past 65: Medicare, IRMAA, and employer coverageThe 20-employee rule that decides whether you can delay Part B, the HSA six-month lookback trap, and why enrolling during peak earning years triggers IRMAA surcharges.
- Medicare Part B late enrollment penalty calculator (and Part D)The Medicare Part B late enrollment penalty adds 10% per year you delay, for life; Part D adds 1% per month. Calculate yours with 2026 premiums.
Go deeper
- Appealing IRMAA: the SSA-44 life-changing-event formMedicare surcharges are priced from two-year-old income. If you retire, lose a pension or lose a spouse, you can ask Social Security to use this year instead. What qualifies, and what never does.
- The HSA triple advantage and its inheritance trapDeduction in, tax-free growth, tax-free medical withdrawals. Plus the receipts strategy, Medicare premiums, and the full-taxation cliff when a non-spouse inherits.
Reference tables
- 2027 IRMAA tiers: what is known, and the 2025 income that sets them2027 IRMAA surcharges are based on 2025 MAGI. What is published so far (the Part D base premium), what CMS has not released yet, and the 2026 tiers for reference.
- 2026 IRMAA tiers: the complete Medicare surcharge tables2026 Medicare IRMAA: Part B and Part D surcharges by 2024 MAGI for individual, joint and married-filing-separately returns, the 2-year lookback and what each cliff costs.
Calculators
- Medicare late-enrollment penalty calculator: Estimate the Part B and Part D penalties that follow a late Medicare enrollment.
- IRMAA calculator: Enter MAGI and filing status to see your Medicare IRMAA tier, Part B and Part D surcharges, and how close the next cliff is.
See it in your plan
If you already have a saved plan, the link only takes you to the right panel; your plan is not changed.
Related topics
This page explains how the rules work. It is not financial, tax or investment advice. Read the disclaimer.
References
- Medicare.gov:Get started with Medicare ↩
- Medicare.gov:When can I sign up for Medicare? ↩
- Medicare.gov:Avoid late enrollment penalties ↩
- CMS: 2026 Medicare Parts A & B premiums and deductibles (IRMAA tables) ↩
- CMS: 2026 Medicare Part D bid information (national base beneficiary premium) ↩
- SSA: Medicare premiums, rules for higher-income beneficiaries ↩
- 20 CFR §418.1205: What is a major life-changing event? ↩
- IRS Publication 969: Health Savings Accounts and other tax-favored health plans ↩
- IRS Rev. Proc. 2025-19: 2026 HSA contribution limits ↩