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Roth Conversion Planner

A conversion pays only if the rate you pay now is lower than the rate you would pay later. First this tool finds your cheap years and works out, dollar by dollar, how much a year is worth converting in them. Then it runs a conversion plan through your whole household — required distributions, Social Security taxation, Medicare surcharges, a surviving spouse, and how the tax is paid — and shows lifetime tax and what is left after tax against converting nothing. For a lot of people the honest answer is to convert little or nothing, and it will say so.

Planning boundary: Federal 2026 brackets and standard deduction, with the age-65 addition (a married couple is assumed to be both 65 or older once you are); Social Security taxation by the IRC §86 formula; Medicare IRMAA surcharges on the 2026 tiers with the two-year lookback, counted as a cost, thresholds rising with inflation; required distributions on each spouse's own clock; and state tax as two flat rates you supply — look them up on the state rates page. Not modelled: the temporary senior deduction, itemized deductions, ACA subsidies, the net investment income tax, AMT, capital-gains harvesting beyond the gains realised when taxable savings are sold, qualified charitable distributions, the five-year clocks, and estate tax. Everything is in today's dollars unless it says otherwise.

Inputs

Your household

Plan name Filing status

Your birth year Ages on this page are yours. Sets your required distribution age: 73 born 1951–59, 75 born 1960 or later. Spouse birth year Sets your spouse's distribution and Medicare ages.

Stop working at age Gross income now Wages before deductions, until you stop.

Annual spending What you actually spend, in today's dollars. Taxes are worked out on top.

Traditional balance All pre-tax accounts combined. Roth balance All Roth accounts combined.

Taxable savings Spent first, which is what opens a cheap window. Cost basis The part of it that is not gain.

Share in older spouse's name Of the traditional balance. Sets whose distribution clock runs on which part.

Your Social Security A year, at your claim age. Claim at age

Spouse Social Security A year, at their claim age. Claim at age Your spouse's age.

Pension a year Fully taxable, rising with inflation. Starts at age

Growth rate

Safe rate

No downturn is modelled here, so use the long-run all-years growth rate (about 10%), not the bucket simulator's calibrated rate. Each account earns its growth share at this rate and the rest at the safe rate.

Inflation Brackets, benefits and spending rise with it.

State rate on the conversion Where you live now. Look it up.

State rate on withdrawals Where you will retire. Often different.

Your conversion plan Rule

Amount each year Today's dollars; it rises with inflation. Never more than the traditional account holds after that year's required distribution. Fill to the top of A survivor's years fill the single bracket of the same rate. Keep income at or under Medicare income (MAGI) in 2026 dollars; premiums follow it two years later. A survivor's years use the single threshold of the same tier.

From age To age

How is the tax paid? Outside funds Taxable savings pay it and the whole conversion reaches Roth. If taxable savings run out, the traditional account pays. From the conversion The tax is withheld, so less reaches Roth. Under 59½ the withheld part is an early distribution with a 10% penalty.

Settings you probably will not change

Pension continues to survivor The election you made when the pension started. Only matters if you entered a pension.

Growth share of each account: the part in growth assets. The rest earns the safe rate.

Taxable, growth share

Traditional, growth share

Roth, growth share

Plan through age

First death at age Your age in your first year alone. Blank for no survivor scenario. Taxable share of the conversion 100% unless your IRAs hold after-tax basis.

The answer

How much is worth converting

These dollar figures are an upper bound: the later rate is taken from the projection with no conversions done, and every year you convert lowers it. They are federal tax in today's dollars, with any difference between your two state rates added to the later rate. The plan below runs the whole household and is the fuller test.

The plan

Your plan, run through the household

The cards above price one future at the rates of your cheapest years, so they are an upper bound. This panel runs the whole household year by year under your assumptions, and it can disagree with them.


Totals	Convert nothing	Your plan

How much to convert

This is a scan of fixed amounts over the ages in your plan, not an optimizer: other ages, and the bracket or IRMAA rules, may do better.

What we can project

Your income against the brackets

What we know exactly

What each dollar costs to convert

Slice converted	Rate now	Tax on the slice	Tax up to here

Supporting detail

Year by year

Age	Spouse	Filing	Conversion	Required distribution	Ordinary income	Taxable Social Security	Bracket	Next dollar	Federal tax	IRMAA	Taxable, year end	Traditional, year end	Roth, year end

Heads-up

Worth knowing before you convert

Method

How this works, and what it refuses to do

What is computed exactly

The cost of converting in a given year is arithmetic. Your filing status, that year's income, the brackets, the standard deduction, the Social Security formula and the capital-gains bands are all known, so the rate on each dollar you convert is known. That is the staircase in the ladder panel, worked out dollar by dollar on the income of your cheapest year. It includes the stretches a bracket table hides: while each extra dollar also makes Social Security taxable, a 10% bracket can cost 18.5% and a 12% bracket 22.2%; and a conversion that pushes the capital gains you realise out of the 0% band costs its bracket rate plus 15%.

What is a guess

The rate you pay later is unknowable. Rather than hide a forecast inside a projection, this tool computes three candidates from your own numbers — the rate in your cheapest years, the highest rate once withdrawals or required distributions begin, and the highest rate a surviving spouse would face filing single — and shows what converting is worth under each.

What the simulation does, year by year

The plan panel runs your whole household twice — once converting nothing, once with your plan — from this year to your plan-through age. It runs in each year's own dollars, with the brackets, the standard deduction, the capital-gains bands and the Medicare thresholds rising with inflation; the Social Security thresholds do not rise, because the law freezes them.

Each year the required distribution comes out first, each spouse's share on their own clock. Spending is what you actually spend, after tax: the tax, any Medicare surcharge and any early-withdrawal penalty are worked out on top of it and drawn in a fixed order — taxable savings, then the traditional account, then Roth. The conversion takes what is left in the traditional account after the distribution and any spending draw. Because the withdrawals that pay the tax are taxed too, each year is solved until the tax and the withdrawals agree.

Paying from outside funds means the year's whole bill, conversion tax included, comes out of taxable savings, which is the real cost of the dollars that stop growing there; when those run out, the traditional account pays. Paying from the conversion withholds its tax, so less reaches Roth, and in years you are 59 or younger the withheld part is an early distribution with a 10% penalty.

Medicare's IRMAA surcharge in each year is set by income two years earlier, charged per person aged 65 or older and counted as a cost. The first two years have no earlier year in the projection and use their own income. In the survivor world you are the survivor: from the first-death age you file single, keep the larger of the two Social Security benefits and the pension's survivor share, both IRAs follow your distribution clock, and spending does not change.

Totals are in today's dollars: each year's figure divided by that year's inflation, then added up. After-tax wealth at the end counts Roth at face value, taxable savings less 15% of the unrealised gain, and traditional money less the tax of drawing it out evenly over ten years on top of your last year's other income, and less the later state rate.

Converting at the same rate you would have paid later is a wash, and beyond the break-even point it is a loss. If you believe tax rates will rise, that belief belongs on the future rate, not in the arithmetic — raise your state rate on withdrawals, or read the survivor card, and the break-even moves right.

The 2026 brackets used here are permanent law: the One Big Beautiful Bill Act (July 2025) removed the scheduled 2026 sunset of the 2017 rates, so "rates go up in 2026" is no longer a reason to convert. The later rates are those same brackets applied to your own projected income; no forecast of Congress is built in.

The survivor scenario is not estate planning. It is the same household's own tax rate during the survivor's own lifetime, and it matters because single brackets are roughly half as wide as joint ones. A surviving spouse's income usually falls while their tax rate goes up.

Reference

Acronyms and terms used on this page

Acronyms

ACA: Affordable Care Act. If you buy health insurance through a marketplace exchange, your premium subsidy shrinks as income rises, so a conversion can raise your insurance cost. Not modelled here.
AGI / MAGI: Adjusted Gross Income and Modified Adjusted Gross Income. Income measures used to test eligibility for various tax benefits; a Roth conversion increases both. For IRMAA this page uses ordinary income including the taxable part of Social Security, plus realised capital gains (tax-exempt interest is not modelled).
AMT: Alternative Minimum Tax. A parallel federal tax calculation that can produce a higher bill than the regular brackets for some filers. Not modelled here.
IRA: Individual Retirement Arrangement (commonly "account"). A tax-advantaged retirement account held in your own name rather than through an employer plan.
IRMAA: Income-Related Monthly Adjustment Amount. A surcharge on Medicare Part B and Part D premiums once income crosses set thresholds. It looks back two years, so a conversion at 65 raises premiums at 67. Modelled here on the 2026 tiers, per person aged 65 or older, with the thresholds rising with inflation, and counted as a cost of the year.
MFJ / MFS / HOH: Married Filing Jointly, Married Filing Separately, and Head of Household. Filing statuses that determine which set of bracket thresholds applies to your income.
NIIT: Net Investment Income Tax. An additional 3.8% federal tax on investment income above certain income thresholds. A conversion is not itself investment income, but it can push other income over the threshold. Not modelled here.
RMD: Required Minimum Distribution. The amount you must withdraw from a traditional retirement account each year once you reach the required age: 73 if born 1951–59, 75 if born 1960 or later. An RMD cannot be converted to Roth and must come out before any conversion that year; this tool always takes it first.

Terms

Roth conversion: Moving money from a traditional (pre-tax) retirement account into a Roth account. You pay ordinary income tax on the converted amount now; qualified Roth growth and withdrawals are then federally tax-free.
Traditional IRA: A pre-tax account. Contributions were generally deducted, growth is untaxed along the way, and withdrawals are taxed as ordinary income.
Roth IRA: An after-tax account. There is no deduction going in, and qualified withdrawals — including growth — come out federally tax-free.
Ordinary taxable income: Income taxed at the regular bracket rates (wages, pensions, IRA withdrawals and conversions, the taxable part of Social Security) after subtracting the standard or itemized deduction. This is the number the brackets are applied to — not your gross pay.
Standard deduction: A fixed amount subtracted from gross income before the brackets apply — $32,200 married filing jointly, $16,100 single, $24,150 head of household for 2026, plus $1,650 per spouse aged 65 or older when married ($2,050 single or head of household). This page includes the age-65 addition and assumes a married couple are both 65 or older once you are. The temporary 2025–2028 senior deduction ($6,000 per person 65+, phasing out above $75,000 / $150,000 of MAGI) is not included, so a 65+ couple's real 0% room in 2026–2028 can be up to $12,000 larger than shown.
Unused deduction: Deduction left over when your income is below it. Those dollars shelter a conversion at 0%, which is why converting after leaving work but before Social Security or required distributions begin is usually the cheapest time to do it.
Cheapest years: The longest run of retirement years in which the first dollar converted costs the least, found in the projection with no conversions. The ladder is measured in the lowest-income one of them.
Marginal rate: The rate applied to your next dollar of income. The "Bracket" column shows the bracket you are sitting in; "Next dollar" is the true cost of one more dollar with everything included — the bracket, Social Security becoming taxable, and capital gains pushed into a higher band — measured on the next $1,000.
Effective rate: Total tax divided by the amount it was charged on — a blend of every rate the income passed through.
Bracket fill: Converting only the amount that fits inside a chosen bracket, so the conversion stops before spilling into the next higher rate. The plan's bracket rule does this every year, Social Security's effect included.
Taxable percentage of the conversion: The share of the converted dollars that is taxable. It is 100% unless you made non-deductible contributions, which create basis.
Basis: After-tax dollars already inside a traditional IRA, or the part of a taxable account that is not gain. Basis is not taxed again when converted or sold.
Pro-rata rule: You cannot convert only the after-tax basis. The IRS treats every conversion as a proportional slice of all your traditional IRA balances combined, which sets the taxable percentage.
Tax withholding: Having tax taken directly out of the conversion. It is convenient, but the withheld dollars never reach the Roth account, and before age 59½ they are an early distribution. The simulation charges the 10% penalty on them.
Outside funds: Paying the conversion tax from taxable savings instead of from the conversion itself. The full conversion reaches Roth, but those savings stop growing. In the simulation, once taxable savings run out the traditional account pays instead, and that withdrawal is taxed too.
Opportunity cost: What the money you spent on tax would have grown to if you had left it invested. The simulation carries it for real: tax paid from taxable savings is money that no longer grows there, which is why paying less tax can still finish behind.
Tax drag: The future tax still owed on a traditional balance. It is the reason a traditional balance and a Roth balance of the same size are not worth the same.
After-tax wealth: What your accounts are worth once the tax still owed on them is taken off: Roth at face value, taxable savings less 15% of the unrealised gain, and traditional money less the tax of drawing it out evenly over ten years and the later state rate. The only fair way to compare a plan that ends with more Roth against one that ends with more traditional money.
First year ahead: The first age at which the plan's after-tax wealth passes that of converting nothing. A plan can be ahead early and fall behind later, or the reverse, so read it with the chart of the difference by age.
Survivor scenario: The same household with one spouse dying at the age you set. From then on you file single, keep the larger Social Security benefit and the pension's survivor share, and spending stays the same. It measures the survivor's own tax, not estate planning.
Age 59½: The age below which withdrawals from retirement accounts generally carry a 10% early withdrawal penalty on top of income tax. A conversion itself is not penalised, but tax withheld from it is a withdrawal; the simulation charges the penalty on withheld dollars in years you are 59 or younger.
Five-year rules: Two clocks. Each conversion has its own five-year clock: withdrawing that converted principal before it runs out triggers the 10% penalty — but only if you are under 59½. Separately, the Roth account itself must be five years old before its earnings come out tax-free, at any age; a first Roth opened by a conversion at 65 has taxable earnings until 70. Neither clock is modelled here.
Capital gains: Profit on investments sold in a taxable account, taxed on its own lower schedule (0%, 15%, 20%). Here, selling taxable savings realises gains in proportion to the unrealised gain, and a conversion can push those gains from the 0% band into the 15% band — a step of its own on the ladder. Harvesting gains on purpose is not modelled.
Social Security taxation: The share of your benefit that is taxable — up to 85% — rises with your other income under IRC §86, whose thresholds are frozen in law. Modelled here: a conversion can make previously untaxed benefits taxable, so in that stretch each converted dollar brings 50 or 85 cents of benefits into tax with it — the "tax torpedo".
.buk file: A BucketSavers plan file, the same household file the site's other tools read and write. It is plain JSON saved to your own computer; nothing is uploaded anywhere. This planner keeps its settings in its own section and leaves what other tools saved there untouched. Saving or opening one also updates the copy of your household kept in this browser, which the household page manages and the other tools open with.