Roth Conversion Ladder: How to Build Tax-Free Retirement Income

Imagine a bucket. Every dollar you put in has already been taxed. Every dollar it earns grows without the IRS taking a cut. And when you take money out in retirement, you pay nothing.

That's a Roth IRA. If you have one, you know how valuable it is. If you don't — or if yours is smaller than you'd like — there's a strategy for filling it, systematically, before the window closes.

It's called the Roth conversion ladder. And for many retirees, it's one of the most valuable financial moves they can make in the years right after they stop working.

A Roth conversion means taking money out of a pre-tax account — a Traditional IRA, a 401(k), a SEP IRA — and moving it into a Roth IRA. You pay income tax on the amount you convert in the year you do it. After that, the money grows tax-free forever.

A Roth conversion ladder is simply doing this in a deliberate, multi-year pattern. Instead of converting a lump sum all at once (and potentially jumping into a high tax bracket), you convert a carefully calculated amount each year — filling your lower tax brackets like water filling a glass, stopping just before it overflows into the next, more expensive tier.

The "ladder" part refers to building up a sequence of conversions over multiple years. Each rung of the ladder becomes tax-free money you can access later.

Here's the counterintuitive part: the best time to do Roth conversions is often right after you retire, before you start collecting Social Security and before your Required Minimum Distributions (RMDs) kick in.

While you were working, your income was high. Doing large Roth conversions on top of a salary meant converting at your highest marginal rate — possibly 24%, 32%, or higher.

Then you retire. Income drops. Maybe to near zero. Suddenly you have room in the 10% and 12% tax brackets that you haven't seen since your 20s.

But this window doesn't last forever. At 63 or 64, Medicare looks back at your income from two years prior to set your premiums (more on this below). At 70, Social Security kicks in and adds to your taxable income. At 73, RMDs begin — and if your Traditional IRA has grown to $1.5 million, those mandatory withdrawals could push you into the 22% or 24% bracket whether you like it or not.

The early retirement years — roughly 60 to 72 — are the sweet spot for conversion planning.

Let's say a married couple retires at age 63. They have $1.2 million in a Traditional IRA and $200,000 in a Roth IRA. Their Social Security won't start until 70. Their annual spending is $75,000.

They decide to draw $50,000 from their Traditional IRA for living expenses and convert an additional $50,000 to Roth each year. Total Traditional withdrawal: $100,000. On a joint return, this keeps their taxable income well within the 22% bracket.

Over five years, they've converted $240,000 from Traditional to Roth — money that will now grow and come out tax-free. They've paid taxes on it at roughly 13–14% effective rates. Had they waited and let RMDs force those withdrawals at 73, they might have paid 22–24%.

The tax savings from a well-executed Roth ladder are real, but the compounding benefit is what makes it extraordinary.

A dollar converted at 12% and then growing tax-free for 15 years is worth far more than the same dollar sitting in a Traditional IRA, growing tax-deferred but eventually forced out at 22–24%.

Beyond tax brackets, Roth accounts have two other advantages that grow in value over time:

1. No RMDs: Traditional IRAs force you to take withdrawals starting at 73. Roth IRAs don't. The money can keep compounding for as long as you live — and then pass to heirs tax-free.

2. Tax-free income doesn't count: Roth withdrawals don't show up in your Modified Adjusted Gross Income (MAGI). That means they don't affect Social Security taxation, they don't trigger IRMAA Medicare surcharges, and they don't count toward ACA premium calculations. Every dollar from Roth is a clean dollar.

The IRMAA lookback

Medicare uses your income from two years ago to set your premiums today. This is called the two-year lookback. A large Roth conversion in year one means higher Medicare premiums in year three.

For 2026, the first IRMAA tier kicks in at $109,000 for single filers and $218,000 for joint filers. Cross that threshold — even by a dollar — and your Medicare Part B premium jumps significantly.

This is one reason conversion planning requires careful projection, not rough estimates. You want to stay under IRMAA thresholds or consciously decide it's worth crossing them in a particular year. For a full breakdown of the IRMAA tiers and how to avoid them, see our post on how to avoid IRMAA.

The ACA cliff (if you're under 65)

If you're buying health insurance on the Affordable Care Act marketplace before Medicare eligibility at 65, be careful. Premium tax credits disappear completely once your income crosses 400% of the Federal Poverty Level — roughly $62,000 for a single person or $84,000 for a couple in 2026.

A Roth conversion that pushes you over that line can cost thousands in lost subsidies. This is one of the sharpest tax cliffs in the entire tax code. For a comprehensive look at conversion-related tax cliffs, including the ACA and IRMAA thresholds, see our post on Roth conversion tax cliffs.

Social Security taxation stacking

Once Social Security begins, up to 85% of your benefit becomes taxable income. A Roth conversion on top of Social Security can amplify the tax bite significantly. This is another reason the window before Social Security starts is the most valuable time to convert.

The single most important decision in a Roth conversion ladder is how much to convert each year. Too little and you waste the low-bracket opportunity. Too much and you cross into a higher bracket, trigger IRMAA, or lose credits you didn't expect to lose.

The right amount to convert is whatever fills your current bracket to just below the next cliff. In practice, that means projecting your full-year income from all sources — Social Security (if already started), dividends, interest, capital gains — and calculating the gap between that and the next threshold.

This math changes every year as your account balances shift, tax laws change, and your income sources evolve. It's worth running the numbers in detail at least once a year.