Strategic planning
Roth Conversion Strategy: When, How Much, and the Ladder Method
Moving money from a Traditional IRA to a Roth IRA is a taxable event, but done strategically in low-income years, it can dramatically reduce lifetime taxes. Here is the full playbook: bracket-filling, the early-retirement ladder, IRMAA trade-offs, and when NOT to convert.
Four Windows When Conversions Make Sense
Low-income years
Gap years between jobs, sabbaticals, early retirement before Social Security. If your taxable income is low enough that you are in the 12% or 22% bracket, each dollar converted costs 12-22 cents in federal tax instead of the 32-37 cents you would pay in a peak-income year.
After market declines
When your Traditional IRA balance is temporarily depressed by a market downturn, you convert more shares for the same dollar of taxable income. If the market recovers, the rebound happens inside Roth.
Before RMDs begin
The window between retirement and your RMD start age (73 for birth years 1951-1959, 75 for 1960+) is prime conversion territory. No mandatory income, potentially lower bracket than peak earning years, and each conversion reduces the future RMD base.
Before Social Security and IRMAA
Social Security income affects IRMAA Medicare surcharges 2 years later. A large conversion at 63 affects IRMAA at 65. Convert in the years before Social Security elections to keep MAGI lower during the IRMAA look-back window.
Bracket-Filling Strategy: The Math
The most tax-efficient approach is to fill your current bracket to the top without spilling into the next bracket. Here is how to calculate the conversion amount:
Worked example: single filer, early retirement, age 62
Wages / taxable income: $40,000
Standard deduction 2026 (single): -$15,750
Taxable income before conversion: $24,250
Top of 12% bracket (single 2026): $48,475
Headroom in 12% bracket: $48,475 - $24,250 = $24,225
Convert $24,225 at 12% rate: $2,907 in federal tax
Cost per Roth dollar: $0.12
If you expect your retirement rate to be 22%+ (from Social Security, RMDs, part-time work), converting at 12% today is a significant win. Each $24,225 converted saves roughly $2,423 in future taxes (10% difference).
Note: 2026 standard deduction and bracket amounts from IRS Rev. Proc. 2025-32. Confirm current figures at IRS.gov before filing.
The Roth Conversion Ladder for Early Retirees
One of the most powerful tools for early retirees (FIRE community) who have most savings in Traditional IRA / 401(k) and plan to retire before 59.5. The ladder solves the problem of accessing IRA money before 59.5 without a 10% penalty.
How the ladder works
| Year (age 50) | Action | Result |
|---|---|---|
| Year 1 (age 50) | Convert $40,000 from Traditional to Roth | 5-year clock starts |
| Year 2 (age 51) | Convert $40,000 | Second clock starts |
| Year 3-4 (age 52-53) | Convert $40,000/yr | Build the pipeline |
| Year 5 (age 54) | Convert $40,000. Withdraw Year 1 conversion ($40K) | Year 1 conversion is now 5 years old: penalty-free |
| Year 6+ (age 55+) | Each year: convert $40K, withdraw previous 5-yr conversion | Steady penalty-free income until 59.5 |
| Age 59.5+ | Withdraw from Roth freely; no penalties, no 5-yr clock for conversions | Full access to all Roth funds |
The 5-year clock for conversion-specific penalty avoidance is separate from the 5-year clock for Roth account eligibility. See withdrawal rules for the full explanation of both clocks.
IRMAA: The Medicare Surcharge Trap
Medicare IRMAA (Income-Related Monthly Adjustment Amount) surcharges are triggered 2 years after the income year. A large Roth conversion at age 63 will cause elevated Medicare Part B and Part D premiums at age 65. This does not necessarily mean conversions are wrong, but the cost must be factored in.
2026 IRMAA Part B thresholds (single filer)
| MAGI (2024 income) | Monthly Part B Premium |
|---|---|
| Up to $106,000 | ~$185 (standard) |
| $106,001-$133,000 | ~$259 |
| $133,001-$167,000 | ~$370 |
| $167,001-$200,000 | ~$480 |
| $200,001-$500,000 | ~$591 |
| Above $500,000 | ~$628 |
Approximate 2026 amounts. Confirm current IRMAA thresholds with CMS before planning conversions.
A large conversion that pushes MAGI from $106,000 to $133,001 triggers a $74/month Part B increase (about $888/year). If the conversion is $27,000, you pay roughly 3.3% of the converted amount in additional IRMAA. Whether that trade-off is worth it depends on your expected future tax savings from having a larger Roth balance.
Practical Rules and Cautions
Do
- + Pay conversion taxes from outside the IRA (cash or taxable account), not from the converted amount. Paying from IRA is equivalent to an early withdrawal on the tax portion.
- + Convert in Q1 to maximize time for converted funds to grow in Roth before year-end.
- + Model the full multi-year scenario before converting large amounts.
Do not
- - Convert in a high-income year just because “Roth is good.” 37% conversion tax rarely makes sense.
- - Forget that you cannot recharacterize conversions (since TCJA 2018). Once done, it is permanent.
- - Convert while taking RMDs without taking the RMD first. RMDs are mandatory and cannot be converted to Roth.