How Much Should I Convert to Roth Each Year? A Bracket-by-Bracket Guide (2026)

"How much should I convert?" is the most common Roth conversion question — and the answer is almost never "as much as possible."

Converting too little leaves money in a ticking RMD time bomb: your traditional IRA grows untouched until age 73, when forced distributions arrive at whatever tax rates exist then. Converting too much wastes bracket space, can trigger Medicare IRMAA surcharges, and may collide with the Social Security tax torpedo. The right amount is a number you calculate, not a guess.

This guide walks through the bracket-filling method, three real examples across different situations, and the four ceilings you need to check before executing any conversion. The 2026 tax brackets and standard deductions are used throughout.

The Bracket-Filling Method

The core concept: convert exactly enough to fill your current tax bracket to the ceiling — without spilling into the next one.

This requires three numbers:

1. Your standard deduction — the amount of income that's tax-free
2. Your other taxable income — pension, wages, dividends, RMDs, taxable SS (not the conversion)
3. Your target bracket ceiling — the top of the bracket you want to fill

The formula:

Maximum conversion = Target bracket ceiling − (Other taxable income − Standard deduction)

If the result is zero or negative, your other income already fills or exceeds the target bracket. Any conversion would be taxed at the next bracket's rate.

2026 Federal Tax Brackets (Taxable Income)

| Bracket | Single | Married Filing Jointly | |---------|--------|----------------------| | 10% | $0 – $12,400 | $0 – $24,800 | | 12% | $12,401 – $50,400 | $24,801 – $100,800 | | 22% | $50,401 – $105,700 | $100,801 – $211,400 | | 24% | $105,701 – $201,775 | $211,401 – $403,550 |

2026 Standard Deductions:

• Single: $16,100 (add $6,000 if age 65+)
• Married Filing Jointly: $32,200 (add $6,000 per qualifying person age 65+)

The 2026 brackets reflect the extended Tax Cuts and Jobs Act rates under OBBBA, locked in through at least 2034. This rate certainty makes multi-year conversion planning considerably more predictable than it was under prior sunset provisions.

Three Real Examples

Example 1: Recently Retired, No Social Security Yet

Situation: Single filer, age 62, recently retired. $15,000/year pension. Target: stay in the 12% bracket.

Calculation:

• Standard deduction: $16,100 (age 62, no senior deduction)
• Other taxable income: $15,000 pension
• Taxable income before conversion: $15,000 − $16,100 = −$1,100 (zero — no tax owed without conversion)
• 12% bracket room: $50,400 − $0 = $50,400

This person has the full 12% bracket open. They can convert approximately $51,500 ($50,400 bracket space + $1,100 of deduction room), keeping total taxable income at or below $50,400.

• Tax on $50,400 conversion (with $15k pension): about $4,500 total federal tax
• Effective rate on the conversion: approximately 8.9%

This person should convert aggressively while income is this low. The $15,000 pension is fully offset by the standard deduction — every conversion dollar is taxed at 10% or 12%. Compare this to a projected 22%+ rate on RMDs at age 75 with the same balance grown for another decade.

Example 2: Married, Both Retired, Social Security Started

Situation: MFJ, ages 67 and 65. Combined SS: $36,000/year. $20,000 pension. Traditional IRA: $900,000. Target: 12% bracket.

Preliminary calculation (ignoring torpedo):

• Standard deduction: $32,200 + $6,000 (spouse age 65) = $38,200
• Pension + provisional income: need to compute taxable SS first
• Provisional income (with zero conversion): $20,000 + $0.5 × $36,000 = $38,000
• At $38,000 provisional income, partially in the 50% phase-in zone (lower threshold for MFJ: $32,000)
• Taxable SS: roughly $3,000 at this income level
• Taxable income before conversion: $20,000 + $3,000 − $38,200 = −$15,200 (still below standard deduction)
• 12% bracket room: $100,800 − $0 = $100,800

That sounds like a large opportunity. But here's the problem: each additional dollar of Roth conversion is also provisional income, pushing more SS into taxation. At this income level, the couple is in the 85% torpedo phase (above the $44,000 MFJ upper threshold once the conversion is added), which means each $1 of conversion effectively generates $1.85 of taxable income.

The actual conversion that fills the 12% bracket ceiling is significantly lower than $100,800 because of this compounding effect. A conversion of roughly $55,000–$65,000 — not $100,800 — will bring total taxable income near the 12% ceiling once the torpedo effect on SS is accounted for.

This is exactly where the Social Security Tax Torpedo Calculator earns its keep. It shows your effective marginal rate at each withdrawal level, letting you identify the exact conversion amount where the ceiling is actually hit.

Example 3: High-Income Retiree, IRMAA Concern

Situation: MFJ, ages 64 and 63. $80,000 in pension and dividend income. No SS yet. Traditional IRA: $1.5 million. Want to convert before Medicare at 65 locks in the two-year IRMAA lookback.

Calculation:

• Standard deduction: $32,200
• Taxable income before conversion: $80,000 − $32,200 = $47,800
• 12% bracket ceiling: $100,800. Bracket room: $100,800 − $47,800 = $53,000
• 22% bracket ceiling: $211,400. Bracket room: $211,400 − $47,800 = $163,600

Both look feasible from a bracket perspective. But this couple is age 63 and 64 — their 2026 MAGI will determine 2028 Medicare premiums.

IRMAA ceiling for MFJ: First cliff at $218,000 MAGI.

• Current MAGI (no conversion): $80,000
• Maximum conversion before IRMAA cliff: $218,000 − $80,000 = $138,000
• 22% bracket room: $163,600

The binding constraint is IRMAA ($138,000), not the tax bracket ($163,600). If they convert $140,000, they cross the $218,000 IRMAA cliff — triggering approximately $1,948/year in additional Medicare Part B and Part D surcharges per person, or $3,896/year total for the couple, for 2028 and likely 2029.

The right conversion: $137,000 — $1,000 below the IRMAA cliff. That's $58,000 more than the 12% ceiling but stays entirely below the IRMAA threshold. Whether the additional 22% bracket conversion is worth paying is a separate question. Use the Medicare IRMAA Calculator to see your exact headroom.

The Four Ceilings to Check Before Converting

Every Roth conversion needs to clear four potential ceilings. Most online calculators check only the first one.

1. Tax bracket ceiling

The top of your target bracket in taxable income. For most retirees, this is the 12% bracket (MFJ: $100,800) or the 22% bracket (MFJ: $211,400). Use the formula above to find your specific bracket room.

2. IRMAA cliff (ages 63+)

Medicare IRMAA uses a 2-year lookback: your 2026 MAGI determines your 2028 Medicare premiums. If you're age 63 or older during the conversion year, a conversion that pushes MAGI over an IRMAA tier can cost $1,948–$5,844 per person per year in surcharges — for two years (the lookback year plus the adjustment year). Even a $1 overage triggers the full tier. Check this ceiling before every conversion in your 60s.

The 2026 IRMAA thresholds: Single at $109k / $137k / $171k / $205k / $500k. MFJ at $218k / $274k / $342k / $410k / $750k.

3. Social Security torpedo zone

If you're receiving Social Security benefits, any additional income — including Roth conversions — is provisional income that can push more of your SS benefit into the taxable zone. In the 85% phase-in tier (provisional income above $34,000 single or $44,000 MFJ), each conversion dollar effectively adds $1.85 to taxable income. At 22%, this produces a 40.7% effective marginal rate — significantly higher than the statutory bracket rate suggests. At 12%, the effective rate becomes 22.2%.

The Social Security Tax Torpedo Calculator shows your effective marginal rate at each income level. Check it before any conversion if you're collecting SS.

4. ACA subsidy cliff (early retirees)

For retirees under 65 on ACA marketplace insurance, conversion income counts as MAGI for premium tax credit purposes. Exceeding 400% of the federal poverty level (~$60,240 for a single person in 2026) can eliminate subsidies worth $10,000–$20,000/year. This ceiling often binds before the tax bracket ceiling for early retirees. The RetireSmarter calculators don't currently model ACA subsidies — this requires a manual check.

The Roth Conversion Ladder Calculator automatically checks ceilings 1, 2, and 3. Ceiling 4 requires a manual calculation based on your specific insurance situation.

When to Convert More, When to Convert Less

Convert more in years when:

• You have little or no other income (recently retired, no SS yet)
• You're before age 63 — no IRMAA lookback concern
• You're before Social Security begins — no torpedo zone
• Brackets are historically low (2026–2034, with the current OBBBA extension)
• Your traditional balance is large and growing, and RMDs will be significant

Convert less in years when:

• You have one-time income events: sold a business, large capital gain, inherited IRA distribution
• You recently crossed an IRMAA cliff and the damage is already done this year
• You're in the active Social Security torpedo zone where each dollar of conversion is taxed at 40%+
• You need to preserve ACA subsidies for marketplace health insurance

Consider converting zero when:

• Your income already puts you near or above your target bracket before any voluntary action
• A large life event (business sale, inheritance) pushes income unusually high for one year
• You're in a high-tax year and expect income to drop significantly next year

The Bottom Line

The optimal Roth conversion amount changes every year as your income, account balances, age, and tax situation evolve. The bracket-filling formula gives you the starting point, but the torpedo, IRMAA, and ACA constraints can cut the number significantly.

Run this calculation annually — ideally in October or November, when you have a clear picture of the year's income and time to execute before December 31. What was optimal in 2025 may not be optimal in 2026.

Use the Roth Conversion Ladder Calculator to model your specific numbers, and the Withdrawal Order Optimizer to see how your conversion strategy interacts with your overall drawdown sequence.

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This article is for educational purposes only and does not constitute tax, financial, or legal advice. Tax laws change — verify all figures with a qualified professional before making financial decisions.