-nan The window between retirement and age 73 (when RMDs begin) is often the best opportunity in your financial life to do Roth conversions. Income is typically lower than your working years, and lower than your RMD-heavy later years. Converting traditional IRA funds to Roth at today’s lower rate can save tens of thousands of dollars in lifetime taxes.
The Roth Conversion Tax Window
| Phase | Typical Income | Roth Conversion Opportunity |
|---|---|---|
| Working years | High (wages) | Poor — high bracket, limited opportunity |
| Early retirement (60-64) | Low if not working | Excellent — low taxable income, large bracket space |
| Pre-RMD retirement (65-72) | Moderate (SS + portfolio) | Excellent — still relatively low; fill brackets before RMDs |
| RMD years (73+) | Higher due to RMDs | Less efficient — SS + RMDs fill brackets; conversions costly |
| Late retirement (80+) | SS + RMDs + maybe limited portfolio | Usually not worth converting; income already forced high |
The sweet spot: Ages 60-72 are typically the lowest-income years in a retiree’s life. Use them. Note that under SECURE 2.0, the RMD start age is scheduled to rise to 75 for people born in 1960 or later — so the “sweet spot” window may extend further for younger retirees.
Who Benefits Most From Roth Conversions
| Profile | Why Conversions Are Valuable |
|---|---|
| Large traditional IRA ($500K+) | Future RMDs will force significant income; converting reduces that burden |
| No pension; low SS | Very low income pre-RMD; huge bracket space available |
| Healthy with long life expectancy | More years to benefit from tax-free Roth growth |
| Heirs who will inherit in high bracket | Converted Roth assets pass tax-free; inherited traditional IRA taxes heirs in 10-year window |
| IRMAA concern on Medicare | Reducing IRA balance reduces future RMD-driven MAGI |
How Much to Convert: Bracket-Filling Method
Step 1: Identify your current taxable income (SS income × 85%, investment income, part-time work, etc.)
Step 2: Subtract standard deduction
Step 3: Find the ceiling of your target tax bracket
Step 4: Conversion available space = bracket ceiling minus step 2 result
2026 Example: Married Filing Jointly
| Income Source | Amount |
|---|---|
| Social Security | $38,000/year |
| Social Security taxable (85%) | $32,300 |
| Dividends/capital gains | $8,000 |
| Standard deduction (2026 MFJ) | $32,200 |
| Taxable income before conversion | $8,100 |
| Target Bracket | Ceiling (2026 MFJ) | Available Conversion Space |
|---|---|---|
| Fill to top of 12% | $100,800 | ~$92,700 |
| Fill to top of 22% | $211,400 | ~$203,300 |
| IRMAA cliff (first tier, MFJ MAGI) | $218,000 | ~$209,900 |
This retiree could convert roughly $92,000-$203,000/year staying in the 12-22% bracket — and up to about $210,000/year before crossing into the first Medicare IRMAA surcharge tier, so filling the 22% bracket in this example keeps them safely under the IRMAA cliff too.
IRMAA: The Hidden Ceiling on Roth Conversions
For retirees on Medicare, the IRMAA (Income-Related Monthly Adjustment Amount) applies when Modified Adjusted Gross Income (MAGI) exceeds thresholds. Roth conversion income adds to MAGI.
2026 Medicare Part B IRMAA tiers (based on 2024 MAGI, since IRMAA is assessed on a 2-year lookback):
| Individual Filer MAGI | Married Filing Jointly MAGI | Monthly Part B Premium (per person) |
|---|---|---|
| $109,000 or less | $218,000 or less | $202.90 |
| $109,000–$137,000 | $218,000–$274,000 | $284.10 |
| $137,000–$171,000 | $274,000–$342,000 | $405.80 |
| $171,000–$205,000 | $342,000–$410,000 | $527.50 |
| $205,000–$500,000 | $410,000–$1,000,000 | $649.20 |
| Over $500,000 | Over $1,000,000 | $689.90 |
These are 2026 premiums based on 2024 MAGI. IRMAA tiers and premiums are indexed for inflation each year — confirm the current tiers at ssa.gov/medicare/pubinfo/cost.html or medicare.gov before relying on this table for a future tax year, since it will change.
Critical: IRMAA is assessed on your income from 2 years prior. A large Roth conversion in 2026 affects Medicare premiums in 2028 — you won’t know the exact 2028 IRMAA thresholds today, so build in a buffer below the current-dollar tier line when estimating.
Strategy: Compare the cost of crossing an IRMAA tier (which applies per person, so a married couple both on Medicare pays the surcharge twice) against the future tax savings from converting. In the 2026 table above, crossing from the first tier to the second tier costs an extra $81.20/month per person (~$974.40/year per person, ~$1,949/year for a couple) — often a small price relative to the tax savings from a well-timed conversion, but worth modeling explicitly.
ACA Subsidy Cliff (Pre-Medicare Retirees Ages 60-64)
If you haven’t started Medicare yet, be aware of the ACA (Affordable Care Act) health insurance subsidy:
| Household Income | ACA Impact |
|---|---|
| Below 400% of the Federal Poverty Level (FPL) | Premium tax credits generally available |
| Over 400% FPL | Enhanced credits phase out or end, depending on current law |
| Very high income | Premium cap rules have changed under recent legislation — confirm current rules |
Federal Poverty Level dollar amounts are published annually by HHS and vary by household size — confirm the current-year FPL and ACA subsidy rules at healthcare.gov, since exact dollar thresholds could not be independently re-verified for this review.
Roth conversion inflates MAGI, which can dramatically increase your ACA insurance costs if you are not yet on Medicare and receiving premium tax credits.
Strategy for ages 60-64: Balance Roth conversion amount against ACA premium impact. Sometimes it’s better to delay conversions until Medicare eligibility at 65 if conversion creates a large ACA penalty.
Roth Conversion vs. Paying Taxes Later: The Math
Should you pay taxes now (conversion) or later (RMD)?
| Scenario | Pay Now (Convert 22%) | Pay Later (RMD 24%) |
|---|---|---|
| Convert $100,000 today at 22% | Pay $22,000 in taxes | $0 today |
| Roth grows 7%/year for 10 years | $100,000 → $196,715 (tax-free) | Traditional IRA: $196,715 |
| RMD at 83 (Uniform Lifetime Table divisor, confirm current table) | $0 | Pay roughly $11,100+ in RMD taxes/year (~24% = ~$2,670) |
| 10-year RMD tax cost | $0 | ~$26,700 |
| Net savings from converting | ~$4,700+ (plus bracket certainty) | None |
The RMD divisor for age 83 is taken from the IRS Uniform Lifetime Table (Pub. 590-B, Table III), which is a fixed actuarial table not adjusted annually like contribution limits — confirm the current published divisor before relying on this figure.
This simplified example shows modest advantage. The advantage grows dramatically when:
- The future tax rate is higher than conversion rate
- The account grows significantly
- RMDs push into IRMAA territory
- Estate planning benefits of Roth to heirs are considered
Roth Conversion and Beneficiaries
| Account Type | Beneficiary Tax Treatment |
|---|---|
| Inherited Traditional IRA | Taxed as ordinary income within 10-year distribution window |
| Inherited Roth IRA | Distributions are tax-free within 10-year window |
If your heirs are in a 22-37% bracket, converting your traditional IRA to Roth at 12-22% is straightforwardly beneficial from an estate perspective.
Sequential Roth Conversion Strategy: Ages 62-72
| Age | Approach | Range to Convert |
|---|---|---|
| 62-64 | Pre-Medicare: balance vs. ACA subsidy | $20,000-$60,000/year |
| 65-69 | On Medicare: fill bracket to IRMAA floor (2026: $218,000 MAGI, MFJ / $109,000 single) | $60,000-$120,000/year |
| 70-72 | SS delayed (70); last window before full RMDs | $50,000-$100,000/year |
| 73+ | RMDs force income; conversions less efficient | Convert only if clearly beneficial |
Common Roth Conversion Mistakes
| Mistake | Why It’s Costly |
|---|---|
| Converting too much in one year (bracket overshoot) | Pushes significant income into 24%+ bracket unnecessarily |
| Ignoring IRMAA thresholds | Crossing a 2026 IRMAA tier boundary can add $81–$185+/month per person to Medicare Part B premiums — check current thresholds annually, since they’re inflation-indexed |
| Forgetting state income taxes | State tax on conversions may make them less attractive in high-tax states |
| Paying conversion taxes from the IRA itself | Reduces conversions efficiency — pay taxes from after-tax accounts only |
| Not converting at all in the tax window | Misses the life’s-best opportunity to shift tax brackets |
| Converting only in the year RMDs begin | Should start 8-10 years earlier for maximum benefit |
For more on Roth IRA strategy and rules, see the Roth IRA hub.
For more on Roth IRA strategy and rules, see the Roth IRA hub.
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