What is IRMAA and how does the two-year lookback work?

IRMAA (Income-Related Monthly Adjustment Amount) is a Medicare Part B + Part D surcharge that kicks in at five income tiers. The SSA uses your MAGI from two years prior to set the current year's surcharge. A Roth conversion at age 63 affects Medicare premiums at 65; conversion at 64 affects 66, and so on. The two-year delay means current-year income decisions have a delayed-impact cost most calculators miss.

What are the 2026 IRMAA brackets?

For single filers: Tier 0 (no surcharge) below $109,000 MAGI; Tier 1 (+$1,322/yr per person) $109K–$137K; Tier 2 (+$3,314/yr) $137K–$171K; Tier 3 (+$5,308/yr) $171K–$214K; Tier 4 (+$7,302/yr) $214K–$500K; Tier 5 (+$7,969/yr) above $500K. MFJ thresholds are 2× single for tiers 1–4 ($218K, $274K, $342K, $428K), but tier 5 MFJ is $750K (1.5× not 2×). Both Part B and Part D surcharges are combined in the surcharge figures.

How do I avoid IRMAA tier crossings during Roth conversions?

Plan conversions so MAGI stays just below the next tier in the years where it matters (ages 63+ for IRMAA-relevant lookback). The projector lets you test scenarios — change a conversion amount in one year and see the Medicare-premium impact two years out, plus the ACA-cliff effect in the same year. Optimizing across the full window requires the multi-year optimizer at /roth-conversion-optimizer/.

IRMAA Surcharge Projection 2026 — Year-by-Year Medicare Premium Calculator

See your Part B + Part D surcharge per year. The Social Security Administration uses your MAGI from two years prior to set the current year's IRMAA — so what you do at 63 hits your premium at 65, what you do at 64 hits at 66. This projector models the two-year lookback across your full pre- and post-Medicare window.

Project your IRMAA surcharges

Same engine as the multi-year Roth conversion optimizer (aca_bridge_optimizer) — joint optimization across tax, ACA cliff, and IRMAA tiers, with the IRMAA-focused view surfaced here.

Current age

Plan end age

Filing status

State

Traditional IRA balance ($)

Taxable account balance ($)

Annual living expenses ($)

Social Security annual benefit ($)

SS claim age

Real return (%/yr)

What IRMAA is and how the lookback works

IRMAA — Income-Related Monthly Adjustment Amount — is a Medicare Part B and Part D surcharge added on top of the standard premium for higher-income beneficiaries. The Social Security Administration determines your tier based on the MAGI reported on your tax return from two years prior. There's no smooth phase-in: cross a threshold by $1 and you pay the full higher tier for the year.

The two-year lookback is the source of most surprises. A Roth conversion at age 63 increases your MAGI in tax year 63, which the SSA sees when setting your premium for age 65. Conversion at 64 hits age 66. Conversion at 65 hits age 67. The window of decisions that affect IRMAA actually starts well before Medicare enrollment.

2026 IRMAA brackets — Single and MFJ

Tier	Single MAGI	MFJ MAGI	Part B + D surcharge / yr
0	< $109,000	< $218,000	$0
1	$109K – $137K	$218K – $274K	$1,322 / person
2	$137K – $171K	$274K – $342K	$3,314 / person
3	$171K – $214K	$342K – $428K	$5,308 / person
4	$214K – $500K	$428K – $750K	$7,302 / person
5	> $500K	> $750K	$7,969 / person

For married filing jointly with both spouses on Medicare, the surcharge applies to each — so the household IRMAA is roughly 2x the per-person number. The projector accounts for this when filing status is MFJ.

How to use the projection

Enter today's age and your IRA balance. The projector runs the multi-year Roth optimization in the background; the IRMAA-tier impact comes from MAGI two years prior so you'll see the cause-and-effect across years.
Set the plan end age. Default 72 because RMDs kick in at 73 — RMDs add to MAGI and frequently push retirees into IRMAA tiers they didn't anticipate.
Compare scenarios. Bump up the Social Security benefit or claim age; the IRMAA-tier years shift. Add state to see how state tax interacts with conversion sizing.
Read the surcharge column. If a row shows IRMAA at age + 2, the year's MAGI crossed a threshold. The optimizer tries to minimize lifetime IRMAA, but sometimes the bracket-fill gain is bigger than the tier hit — that's the joint-optimization tradeoff the engine resolves.

Common IRMAA-triggering events

Roth conversion year — every dollar converted counts as ordinary income and increases MAGI.
RMD year — required distributions begin at age 73 under SECURE Act 2.0; for big traditional balances they can dominate MAGI.
Capital-gain harvesting — long-term gains are part of MAGI even though they're taxed at LTCG rates.
Pension / annuity start — full payments flow into MAGI.
Inherited IRA — required to be drained within 10 years under SECURE; large lump-sum distributions can push you up multiple tiers.

Related calculators

Multi-year Roth conversion optimizer — same engine, conversion-schedule focus
ACA premium subsidy + cliff calculator — the pre-65 income-tier game
Retirement calculator — full Monte Carlo with IRMAA + ACA + state tax
Methodology — how the joint optimizer works

FAQ

Is IRMAA permanent once I cross a tier?

No — it resets every year. The SSA recalculates each year based on the MAGI from two years prior. If your MAGI drops back below a tier threshold, your premium drops the following year (with the same two-year lag).

Can I appeal an IRMAA determination?

Yes — life-changing events (retirement, divorce, death of a spouse, etc.) qualify for SSA-44 form reconsideration. The projector doesn't model the appeal process; it shows the default determination.

What about Part C and Medigap?

IRMAA applies to Part B and Part D only. Part C (Medicare Advantage) plans embed Part B premium so the surcharge passes through; Medigap is unaffected.