What it is
TL;DRA Roth conversion ladder is a multi-year plan that moves traditional IRA dollars into a Roth IRA in bracket-managed slices, paying voluntary tax now to fill the 12%, 22%, or 24% brackets, so that future RMDs and surviving-spouse income don't push you into 32%+.
RMDs start at 73 (rising to 75 in 2033). For owners with $2M-$5M of pre-tax retirement assets and Social Security, RMDs can push taxable income well into the 32-35% bracket and trigger IRMAA Medicare surcharges.
The window between retirement (often early 60s) and Social Security claiming (often 67-70) is typically the lowest-income years of a high earner's life. That window is when Roth conversions are most powerful.
Who it's for
Owners aged 55-73 with significant pre-tax retirement balances, a clear retirement window, and the cash outside the IRA to pay the conversion tax.
- ✓Recently retired owners with $1.5M+ in traditional IRAs/401(k)s
- ✓Couples planning to delay Social Security to 70
- ✓Anyone expecting RMDs that exceed needed spending
- ✓Owners with a sale year that produced extra after-tax cash
- ×People who can't pay the conversion tax from non-retirement money
- ×Pre-retirees still in 32%+ brackets where conversions don't beat current rates
- ×Owners with significant after-tax money in IRAs (pro-rata rule muddies the math)
How it works
1. Model the no-conversion baseline
Project taxable income year by year from now through age 95, including Social Security, RMDs, pension income, and surviving-spouse single-filer status. Identify the years (and brackets) where conversion saves tax.
2. Choose annual conversion amounts that fill, but don't overflow, brackets
Common targets: top of the 22% bracket for moderate balances, top of the 24% bracket for larger balances. Don't push into 32% unless future projections show 35%+.
3. Pay the conversion tax from non-IRA funds
Withholding conversion tax from the IRA itself is mathematically inferior, those dollars never grow tax-free. Use brokerage, savings, or sale-year proceeds.
Watch IRMAA. Medicare premium surcharges based on MAGI two years prior can swallow much of the conversion savings if you push too far in any single year.
4. Watch the five-year rules
Each conversion starts its own five-year clock for tax-free principal withdrawals. Less of an issue after 59½, but critical for early-retirement ladders.
A worked example
Jim and Carla are 64, just retired, with $2,800,000 in his rollover IRA and $400,000 in her IRA. Spending need is $140,000/yr from taxable accounts until they claim Social Security at 70. Effective marginal rate is the 12% bracket. Project to age 95.
| No conversions | $120k/yr conversion ages 64-69 | |
|---|---|---|
| Lifetime federal tax (projected) | $1,420,000 | $1,160,000 |
| RMDs starting at 73 | $148,000 yr 1 | $96,000 yr 1 |
| Surviving-spouse single-filer tax spike | $48,000/yr higher | $22,000/yr higher |
| Roth balance at age 80 | $0 | $1,180,000 |
| Projected lifetime tax saved | ≈ $260,000 |
Six years of $120k conversions cost them about $86k of tax now (12% + 22% brackets), but save roughly $260k in projected lifetime tax, and leave heirs a $1.2M tax-free Roth.
Limits and risks
The pro-rata rule blends all traditional IRA balances when determining the taxable portion of any conversion. After-tax IRA money complicates the math; roll it out to a 401(k) first if possible.
Conversion strategies become less attractive if tax rates fall. A future return to pre-TCJA brackets makes today's conversions look smart; a sustained rate cut makes them look unnecessary.
Conversion mechanics are well-trodden and rarely audited. The two common errors are missed Form 8606 (after-tax basis tracking) and trustee-to-trustee transfer mistakes that get reported as distributions. Both are paperwork problems, not substance problems.
IRS reference
- IRC §408A(c)Roth IRA contribution and conversion rules.
- IRC §401(a)(9)Required minimum distribution rules, what conversions help avoid.
- Notice 2014-54Pro-rata rule for after-tax IRA dollars during conversion.