2026 IRMAA brackets — Medicare Part B by income
Where the 2026 adjustment starts
$109,000
A single filer whose 2024 modified adjusted gross income stayed at or below $109,000 paid the standard $202.90. One dollar above it, the premium became $284.10.
- Standard premium
- $202.90
- First threshold, single
- $109,001
- Highest tier
- $689.90+$487.00 adjustment
- Income year used
- 2024two tax years back
The adjustment is a cliff, not a slope. There is no phase-in across a bracket: one dollar of extra income at a threshold moves the whole premium to the next tier, and the step at the first threshold in 2026 was $81.20 a month — $974 over the year for one dollar of income.
| Single | Married filing jointly | Married filing separately | Adjustment | Total Part B | Part D adjustment |
|---|---|---|---|---|---|
| Up to $109,000 | Up to $218,000 | Up to $109,000 | none | $202.90 | none |
| $109,001 to $137,000 | $218,001 to $274,000 | — | $81.20 | $284.10 | $14.50 |
| $137,001 to $171,000 | $274,001 to $342,000 | — | $202.90 | $405.80 | $37.50 |
| $171,001 to $205,000 | $342,001 to $410,000 | — | $324.60 | $527.50 | $60.40 |
| $205,001 to $499,999 | $410,001 to $749,999 | $109,001 to $390,999 | $446.30 | $649.20 | $83.30 |
| $500,000 and above | $750,000 and above | $391,000 and above | $487.00 | $689.90 | $91.00 |
Married filing separately is not a middle path
A married person who filed separately and lived with their spouse gets three tiers rather than 6: the standard premium up to the first threshold, then a jump straight to $649.20, then the top tier. The intermediate brackets do not exist for that filing status. This is routinely mis-tabulated by summaries that reuse the single-filer ladder.
Checking the table against the statute
The tiers are not arbitrary. The statute sets each one as a share of the total cost of Part B coverage — roughly 35, 50, 65, 80 and 85 percent against the standard 25 percent — so each total should be close to the standard premium multiplied by 1.4, 2.0, 2.6, 3.2, 3.4. Reconstructing the published table that way is how this site checks it independently of the notice it came from.
| Tier | Published total | Standard × multiplier | Difference |
|---|---|---|---|
| Tier 1 — ×1.4 | $284.10 | $284.06 | +$0.04 |
| Tier 2 — ×2.0 | $405.80 | $405.80 | +$0.00 |
| Tier 3 — ×2.6 | $527.50 | $527.54 | -$0.04 |
| Tier 4 — ×3.2 | $649.20 | $649.28 | -$0.08 |
| Tier 5 — ×3.4 | $689.90 | $689.86 | +$0.04 |
Why the reconstruction never lands exactly, and why that is correct
CMS computes each tier from the unrounded monthly actuarial rate. What gets published is the standard premium already rounded to a dime, so multiplying the rounded figure carries that rounding error up through the multiplier and the tier’s own rounding adds a little more. A build that demanded exact equality here would fail on correct data — and the tempting fix, rounding the reconstruction to the nearest dime, makes it worse, not better. The check this site runs is a per-tier tolerance of 0.05 × the multiplier plus 0.055, with exact equality reserved for the committed table against its own Federal Register source.
Part D, which reconstructs exactly
The Part D adjustment behaves differently and can be reproduced to the cent. Each amount is the national base beneficiary premium of $38.99 times the tier’s share above the standard 25.5 percent, rounded to the nearest ten cents. That formula reproduces every published amount exactly, at that base and at no other — which is itself the strongest available confirmation of the base.
The Part D ladder and the arithmetic behind it.
Related
- Every IRMAA year14 committed
- Part B 2026$202.90
- How IRMAA worksthe mechanism
- Your bracketcalculator
- Hold harmlessand why IRMAA blocks it
- Part D IRMAAthe second ladder
Sources and freshness
- Federal Register — Medicare Program; Medicare Part B Monthly Actuarial Rates, Premium Rates, and Annual Deductible Beginning January 1, 2026 — verified 10 August 2026
- SSA POMS HI 01101.020 — Income-related monthly adjustment amount — verified 10 August 2026
CMS computes each tier from the unrounded monthly actuarial rate, so exact reconstruction from the rounded standard premium is impossible. SPEC section 3.7 fixes the tolerance at $0.10, which holds for 2026 but is not the right bound generally: the standard premium carries up to $0.05 of rounding error, multiplying it by 3.4 propagates that to $0.17, and the dime rounding of the tier itself adds another $0.05. The bound is therefore per-tier. Never round the reconstruction, and never assert exact equality against it. Exact equality is asserted only between the committed tables and their Federal Register / POMS sources.
Figures effective 1 January 2026. Page figures last verified against the sources above on 10 August 2026. Corrections: the correction log · support@inventum.com.au