Neither the backdoor Roth nor the mega backdoor Roth uses this adjustment - both are Cash Flow Priorities, covered in Backdoor and mega backdoor Roth. This page is about converting money you already hold in a Traditional account.

A Roth Conversion adjustment moves dollars from a Traditional retirement account into a Roth retirement account in a specified year. The converted amount is treated as fully taxable ordinary income in the conversion year, then sits in the Roth account where future growth is tax-free.

How the adjustment works

• Choose the source Traditional account and the destination Roth account.
• Enter the conversion amount in today's dollars.
• Set the year (one-time) or recurring window the conversion applies to.

In the conversion year, the engine adds the amount to ordinary income (which can push you into higher tax brackets and affect IRMAA, ACA subsidies, and Social Security taxability), debits the Traditional account, and credits the Roth account.

Set amounts vs the Roth Optimizer

With Auto mode (fill to bracket) off, a Roth Conversion adjustment converts the dollar amount you enter. With it on, the Roth Optimizer sizes each year's conversion for you, to fill a bracket or stay under an IRMAA tier. Turn it on when you want the simulation to decide how much to convert each year. Roth conversions, either way, are a Pro feature. Without Pro, conversions added earlier stay in your plan and still run; you can switch them off or remove them, but not edit them.

Reading the conversion rationale

In the year detail on the Proof view's Year by year tab, every conversion that actually moved money shows as a purple Roth Conversion row. Click the row to expand a "Why this conversion?" panel that shows how that year's amount was sized. What you see depends on the mode the adjustment was set to:

• Fill to a bracket. Top of your target bracket, plus your deduction, minus the income you already had, equals the room left in the bracket. Conversions run last in the year, after spending, market returns and rebalancing, so that income includes any Traditional money your spending drew, which has first claim on the bracket, and any gains your rebalance realized. The converted money starts growing in the Roth the following year. With Social Security, it also includes the part of your benefit that is taxable, which grows with the conversion and with the year's capital gains and dividends, and the panel says when it counted them.
• ACA limit. When the ACA subsidy cap is on and a healthcare adjustment is active, the panel adds a second block: the 400% federal-poverty-level ceiling, minus your income for the year so far, equals the room left under the ceiling. The limit applies whatever bracket you picked, so a 22% or 24% fill stops at the ceiling too. If your income was already past the ceiling before converting, the panel says so instead of showing the arithmetic. The same limit applies to a fill-to-IRMAA-tier conversion.
• IRMAA limit. When the IRMAA cap is on, in any year a Medicare bill will read, a bracket fill also stops a small safety buffer under the next IRMAA tier, and the panel shows the tier threshold, the buffer and the room they left.
• Fill to an IRMAA tier. The tier's income threshold, minus a small safety buffer, minus your income for the year so far, equals the room left below the tier. That income includes the year's dividends, the taxable withdrawals that funded your spending, and the capital gains those withdrawals realized. Social Security counts at its taxable share, which rises with the conversion, so with a benefit the room is solved rather than subtracted. Picking the top tier means there is no upper limit, so the amount you specified is converted.
• Fixed amount. No arithmetic. The panel says the amount is the one you set.

The last line names the binding constraint. The single thing that stopped the conversion from being larger: the top of your tax bracket, the ACA subsidy ceiling, your IRMAA tier ceiling, the balance available in the source account, or simply the amount you specified. If it says the source account balance, the plan wanted to convert more than the account held.

Years where no conversion happened have no purple row and no panel. The panel explains how a conversion was sized, not why one did not fire.

A Roth Conversion with Auto mode off records a manual conversion: a specific dollar amount you intend to do in specific years. The two are independent: a plan can use Auto conversions alone, manual conversions alone, or both layered together.

Seeing conversions across the whole plan

The Taxes view on Proof (a Pro view) shows the conversions year by year. By source stacks each year's ordinary income by where it came from, with Roth conversions as their own band, drawn against that year's deduction and bracket tops. By bracket shows how far each year's taxable income reaches into the brackets, with a dashed line at your bracket-fill target, so you can see which years the conversions filled and which ones RMDs pushed higher.

Comparing whole-plan strategies

Explore tax strategies, at the top of the Tax Strategy section or of a Roth Conversion's settings, opens the Tax Strategy Explorer. It compares strategies across the whole plan against a goal you choose and can save one as a new scenario.

A conversion saved from the explorer may carry limits, such as a yearly cap or a cash reserve. They are listed on the conversion and are read-only there; change them by running the explorer again.