How to model a Roth conversion ladder in Deorbit Plan

Last reviewed July 2026 · 5 min read

A Roth conversion ladder moves money from pre-tax accounts into Roth on purpose — a slice each year, taxed at rates you choose — instead of waiting for required minimum distributions to force the income out at whatever rate your 70s and 80s bring. The companion article on the ladder itself covers the why (the 5-year seasoning rule, gap years, the RMD deadline). This one is the how: setting up a ladder in Deorbit Plan and reading the charts that tell you whether it earns its tax bill.

The lever: fill-the-bracket conversions

The workhorse strategy is fill the bracket: each simulated year, convert pre-tax → Roth until ordinary income reaches the top of a federal bracket you pick, and pay the conversion tax from other accounts. For 2026, the 22% bracket tops out at $211,400 of taxable income on a joint return ($105,700 single), and the 24% bracket at $403,550 joint — so a retired couple with modest other income can convert six figures a year without touching the 32% rate. The simulator applies the standard deduction and each path’s own inflation indexing for you; you only choose the bracket.

Step 1 — choose a conversion strategy

Open the Strategy panel and find the Roth conversions group. The Conversion strategy selector has four options: No Roth conversions, Fixed amount per year, Fill bracket (retired years), and Fill bracket (incl. working years). For a classic ladder, pick Fill bracket (retired years) — conversions run only in years when wages are no longer stacking on top. The working-years variant exists for high savers who want to fill the 24% or 32% bracket on top of a salary.

Step 2 — set the bracket top and the ages

Three fields appear. Fill to top of bracket offers 12%, 22%, 24%, or 32%; lower brackets prepay less tax per year but convert less, so an RMD problem may survive. Start age is usually the first retirement year — the gap years before Social Security and RMDs are the cheap ones. Stop age defaults to 75, and the field’s own hint says why: conversions usually stop by RMD age (75 for anyone born 1960 or later under SECURE 2.0), because once RMDs start they fill the low brackets themselves.

Step 3 — guard the cliffs

Below the bracket picker sits “Stay this far below the nearest cliff ($, today’s)” — the cliff-margin guard. It additionally caps each year’s conversion so MAGI keeps your chosen buffer under the nearest cliff above it: the ACA 400%-of-poverty subsidy cliff while anyone under 65 buys marketplace coverage, and each IRMAA tier boundary once anyone is 65 or older (the first 2026 tier starts at $218,000 joint / $109,000 single). One dollar past either line costs real money, so a few thousand dollars of margin is cheap insurance; 0 turns the guard off.

Step 4 — read the results

Four dashboard views tell the story. The Taxes & MAGI chart shows tax bars spiking during the conversion years — that is deliberate prepayment — while the MAGI line rides below the dashed ACA and IRMAA threshold lines; a crossing means a cliff bites. The Account buckets chart shows the pre-tax band shrinking into the Roth band: the ladder working. The Forced RMDs vs spending need chart is the payoff test — bars towering over the spending line are the RMD bomb, and a good ladder flattens them. Finally, compare the Lifetime tax (median) stat tile before and after: a ladder only wins if the lifetime total falls. Turn on the Events toggle to see “Roth conversions begin” and “First Roth ladder rung matures” markers (the 5-year seasoning clock) on every chart.

Step 5 — compare strategies instead of guessing

The bracket choice is an empirical question, not a doctrine. The panel’s “Compare them in the Strategy Lab” link opens the Lab’s strategy sweep, which runs your profile under every conversion strategy (none, fill 12/22/24/32%) crossed with Social Security claim ages, using the same market draws for every point. Every result also reports its closest cliff approach. Click a promising point and Load as Scenario B to see the full A/B — with a fixed RNG seed in Market Assumptions, any gap is your strategy, not luck.

Try it in Deorbit Plan

In the Strategy panel, set Conversion strategy to Fill bracket (retired years), pick a bracket top and start/stop ages, and set the cliff-margin guard. Watch the Taxes & MAGI, Account buckets, and Forced RMDs vs spending need charts, then run the Strategy Lab sweep to compare bracket tops on the success-vs-lifetime-tax frontier.

Educational content only — not financial, tax, or investment advice.

See how this plays out with your own numbers. Try it in the simulator →