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Roth Conversion Strategy Planner

Prices a conversion at its true marginal cost — not the bracket alone, but the Social Security it drags into income, the capital gains it pushes off the 0% rate, the senior deduction it phases out, the net investment income tax, the IRMAA surcharge two years out and the marketplace credit at the 400% line — then tells you how far you can convert before the next threshold moves.

Income before the conversion Form 1040 lines 1–8

Everything the household expects to report this year without the conversion. The conversion is added on top of these figures.

Wages and salaries

Net self-employment income Schedule C or K-1 ordinary income

Pensions and annuities Taxable portion, excluding any RMD below

Required minimum distributions Taken first — an RMD can never be converted

Taxable interest

Tax-exempt interest Untaxed, but counts for Social Security and IRMAA

Ordinary dividends Non-qualified portion only

Qualified dividends

Net long-term capital gain After losses; enter a net loss as a negative

Net short-term capital gain

Rents, royalties, other ordinary Schedule E and anything not listed above

Adjustments to income HSA, deductible IRA, half of SE tax

Social Security 1040 line 6a · Pub 915

Gross benefits, before any Medicare premium is withheld. Each conversion dollar can drag up to 85 cents of benefit into income with it, which is how an ostensible 12% bracket becomes 22.2%.

Your gross benefits

Spouse gross benefits

Net investment income tax Form 8960 · §1411

A conversion is never net investment income, but it raises MAGI — so it can pull existing interest, dividends and gains into the 3.8% tax. Those are counted automatically from the figures above.

Passive rental or other NII above

Expenses allocable to NII

The conversion Form 8606 part II

Amount to convert this year

$0$200,000$400,000

Traditional IRA balance at 12/31 All traditional, SEP and SIMPLE IRAs, including this conversion

Nondeductible basis in those IRAs Form 8606 line 14 carried forward

The pro-rata rule treats every converted dollar as the same blend of basis and pre-tax money across all traditional IRAs combined — the basis cannot be converted on its own. A 401(k) balance stays outside this calculation unless it has been rolled to an IRA.

How the tax gets paid 1040 line 25b · Form 5329

Source of the tax payment

Withholding from the IRA is the expensive choice. The withheld dollars never reach the Roth, and under age 59½ they are an early distribution carrying the 10% additional tax. Paying from outside funds is economically the same as making a larger contribution.

Staging across years Planning

Repeats the same conversion for the number of years shown, with brackets and the standard deduction indexed and other income growing at the rates set here. Use it to find the year a multi-year fill crosses a threshold.

Years of conversion

Bracket indexing %

Growth on other income %

Growth on the IRA %

Year	Converted	Fed + state	Marginal	IRA left

Medicare premium surcharge (IRMAA) Form SSA-44 · two-year lookback

A conversion in the year chosen at the top sets the premium two calendar years later. IRMAA is a cliff rather than a phase-in: a single dollar over a threshold applies the whole tier, to each spouse on Medicare, for a full year.

People on Medicare in the premium year

MAGI tier	Part B + D, each	Status

Surcharges are the published 2026 premium-year amounts, used as a stand-in for the premium year two years out, which CMS has not yet announced. Thresholds are indexed annually; the top tier is frozen until 2028.

Marketplace premium credit Form 8962

For anyone under 65 buying coverage on the exchange. The enhanced credit expired after 2025, so 400% of the federal poverty line is a cliff again: one dollar over and the entire advance credit is repaid.

Marketplace household size

Advance credit received for the year Zero if not on a marketplace plan

Poverty guidelines are the 2025 figures governing 2026 coverage, continental US; Alaska and Hawaii are higher. A bill restoring the enhanced credit passed the House in January 2026 and has not become law — confirm where it stands before relying on the cliff.

This is a projection, not a prepared return. It models federal tax, the Social Security inclusion worksheet, the preferential rate stack, the senior deduction phase-out, the net investment income tax, IRMAA and the marketplace credit cliff. It does not model the alternative minimum tax, the QBI wage and property limits, state-specific retirement income rules, or the five-year clocks governing withdrawals. A conversion is irrevocable — recharacterizing one has not been possible since 2018. Nothing entered here leaves your browser. Confirm any conversion with your preparer before executing it.

Sure Financial and Tax Services LLC · Surya Padhi, CPA, EA · 908-955-0696 · contact@suryapadhiea.com

Roth Conversion Strategy Planner

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