Medicare enrollment and IRMAA: the dates and the income test
Medicare has a seven-month window around your 65th birthday, and higher incomes pay an extra monthly amount called IRMAA that is based on a return from two years earlier. We cover both.
Prepared by Prem Tax and Accounting Corp. Last reviewed November 6, 2026. Figures as of November 6, 2026.
Medicare gives you a seven-month window around your 65th birthday to sign up, and missing it can bring a late penalty. Higher incomes also pay IRMAA (income-related monthly adjustment amount), based on a return from two years earlier. We line up the dates and income with the Two-Years-Back Mailbox Check, part of our retirement series.
- Your first window runs from 3 months before to 3 months after the month you turn 65.
- The Part B late penalty is 10 percent of the premium for each full 12 months you waited, usually for as long as you have Part B.
- The 2026 Part B premium is $202.90 a month. The 2027 premium is not published as of November 6, 2026.
- IRMAA uses income from two years back. 2026 premiums use 2024 returns.
Source: CMS fact sheet, November 14, 2025
Our 2027 planning figure for the first surcharge is about $112,000 single or $224,000 joint (2025 income). We computed it from the law's price-index formula, and Medicare has not confirmed it. A missing October 2025 index figure leaves other tiers uncertain, so we show none.
An invented example
A married couple file jointly with $190,000 of income. A $40,000 Roth conversion in 2026 lifts it to $230,000 and affects 2028 premiums, whose limits are unknown. Using the 2026 table only to show a cliff, $230,000 falls in the first tier (over $218,000, up to $274,000). Each spouse pays $81.20 more for Part B and $14.50 more for Part D a month, which is $1,148.40 a year each and $2,296.80 for both. A $28,000 conversion lands exactly on $218,000: no surcharge.
The Two-Years-Back Mailbox Check
- If you still work, ask whether your coverage counts as current-job coverage.
- Stop HSA contributions at least 6 months before you apply.
- Look at your return from two years ago. Its income may set your surcharge letter.
- Before a Roth conversion or large sale, ask which premium year it affects.
Common questions
Can an IRMAA decision be changed?
Yes. Social Security may use a more recent year if income dropped because of a listed life-changing event, such as marriage, divorce, a spouse's death, work stopping or loss of a pension. Use Form SSA-44. A Roth conversion is not on the list.
Does COBRA let me wait to sign up for Part B?
No. COBRA and retiree coverage are not current-job coverage, so waiting can lead to a late penalty.
When will the 2027 premiums be announced?
Not yet, as of November 6, 2026. The 2026 amounts came out November 14, 2025. Our [2027 figures page](/current-topics/year-end-2027/2027-figures-and-limits/) will carry them.
Official sources
- Medicare.gov: when can I sign up for Medicare
- Medicare.gov: avoid late enrollment penalties
- CMS: 2026 Medicare Parts A and B premiums and deductibles
- SSA: Medicare premiums, rules for higher-income beneficiaries
- Cornell Law: 42 U.S.C. 1395r, income-related premium rules
- IRS: Publication 969, health savings accounts
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