The 2026-to-2028 IRMAA timeline
For 2026 Medicare premiums, SSA generally uses MAGI from the 2024 federal tax return. If 2024 information is unavailable, SSA may use 2023 information.
This is the basis for explaining the commonly described two-year IRMAA lookback. Under that normal process, income reported for tax year 2026 would generally be used when SSA determines income-related Medicare premiums for 2028.
The 2028 thresholds and premium amounts are not yet available. The 2026 brackets should not be applied to a 2028 determination.
Sources: SSA Medicare premiums · SSA Program Operations Manual for 2026 IRMAA
MAGI has a specific IRMAA definition
For IRMAA, SSA defines MAGI as:
Adjusted gross income plus tax-exempt interest income
SSA’s Form SSA-44 points to Form 1040, line 11 for adjusted gross income and Form 1040, line 2a for tax-exempt interest.
This definition should not be confused with the modified AGI calculations used for Roth IRA contribution eligibility or other tax provisions.
Sources: SSA Medicare premiums · Form SSA-44
Why a Roth conversion can increase IRMAA MAGI
The previously untaxed portion of money converted from a traditional retirement account to a Roth account is generally included in gross income for the conversion year. That taxable conversion income flows into AGI and can therefore increase the MAGI SSA later uses for IRMAA.
- A conversion is not automatically taxable dollar for dollar.
- Nondeductible IRA basis and other after-tax amounts can affect the taxable portion.
- Form 8606 is used to report traditional IRA-to-Roth IRA conversions and calculate relevant taxable amounts.
- The special MAGI calculation used for Roth contribution eligibility can exclude conversion income. That is not the IRMAA MAGI calculation.
Sources: IRS Publication 590-A · IRS Form 8606 information · IRS Form 8606 instructions · IRS Roth account guidance
The 2026 standard Part B premium
The standard Medicare Part B premium for 2026 is $202.90 per month.
The 2026 Part B annual deductible is $283, although the deductible is not central to this discussion.
Source: CMS 2026 Medicare Parts B premiums and deductibles
The 2026 Part B IRMAA thresholds
These are 2026 premium-year figures based generally on 2024 MAGI. They are not 2028 projections.
| Individual return | Married joint return | Monthly IRMAA | Total monthly Part B premium |
|---|---|---|---|
| $109,000 or less | $218,000 or less | $0 | $202.90 |
| Above $109,000 through $137,000 | Above $218,000 through $274,000 | $81.20 | $284.10 |
| Above $137,000 through $171,000 | Above $274,000 through $342,000 | $202.90 | $405.80 |
| Above $171,000 through $205,000 | Above $342,000 through $410,000 | $324.60 | $527.50 |
| Above $205,000 but below $500,000 | Above $410,000 but below $750,000 | $446.30 | $649.20 |
| $500,000 or more | $750,000 or more | $487.00 | $689.90 |
Married-filing-separately taxpayers have a different CMS scale and should use the official CMS table.
Source: CMS 2026 Medicare premium fact sheet
IRMAA can affect Part D too
IRMAA is not limited to Part B. People with sufficiently high MAGI may also owe a monthly income-related adjustment for Medicare Part D.
The 2026 Part D income-related monthly adjustments are $14.50, $37.50, $60.40, $83.30, or $91.00, depending on the applicable income tier. These are paid in addition to the person’s plan premium.
Source: SSA Medicare premiums
A Roth conversion is not an SSA life-changing event
SSA lists eight life-changing events on Form SSA-44:
- Marriage
- Divorce or annulment
- Death of a spouse
- Work stoppage
- Work reduction
- Loss of income-producing property
- Loss of pension income
- Employer settlement payment
A Roth conversion is not on this list. Therefore, the conversion itself does not qualify someone for life-changing-event relief from IRMAA.
A person might separately experience a qualifying event, such as retirement or reduced work. In that situation, SSA may consider more recent income information when the required evidence is provided. That is separate from the conversion.
Sources: Form SSA-44 · SSA request to lower IRMAA
Why IRMAA should not control the entire decision
IRMAA is a potential cost, but it is not automatically a reason to avoid a Roth conversion. A complete evaluation can include:
- Current versus expected future tax rates
- Future required minimum distributions
- Social Security taxation
- Medicare Part B and Part D costs
- Cash available to pay conversion taxes
- The length of the planning horizon
- Survivor filing status
- Estate and beneficiary objectives
- The value of future tax-free Roth distributions
Why “convert up to the IRMAA cliff” is incomplete planning
- Threshold-based premiums create step changes.
- Future brackets are unknown.
- Taxable income can change through several interacting items.
- A one-year surcharge may need to be compared with longer-term tax consequences.
Evaluate taxes and healthcare together
- When will Medicare coverage begin?
- Which tax return is SSA likely to use?
- How much of a proposed conversion would be taxable?
- What other income may affect AGI?
- Could the conversion alter Social Security taxation?
- Are both spouses Medicare-enrolled?
- Is there a separate SSA-qualifying life event?
- What are the multi-year tax and estate objectives?
Model the connection
IRMAA should be modeled, not feared or ignored. A Roth conversion decision should be evaluated within a multi-year retirement plan that connects taxes, income, healthcare, and risk.
Continue learning: Why a high yield alone does not make a retirement plan, how Roth conversions can affect Social Security taxes, or return to RetireDividend Learn.