Roth Conversion Ladder Calculator
The rungs, the tax, and the wait
Your result will appear here
Fill in the fields on the left and this updates as you type.
Know what this estimate is based on
- Jurisdiction
- General mathematical model
- Scope and limitations
- Long-range scenario, not a guarantee. Small changes in returns, inflation, fees, taxes, and withdrawal timing can materially change the result.
- Source links checked
- Jul 30, 2026
Built and regression-tested by Smart Tools Lab. It has not been individually reviewed by a licensed financial, tax, or legal professional.
How to use
- 01
Enter the age you start converting. Everything on the page counts forward from it, and it is what decides how many rungs there is still time to build.
- 02
Enter the annual spending each rung has to fund, then the amount you plan to convert each year. They are separate fields on purpose — a rung sized to a tax bracket and a rung sized to a year of spending are rarely the same number.
- 03
Enter the effective tax rate you expect on each conversion. Effective, not marginal: a conversion in a year with no wages fills the brackets from the bottom, so the rate across the whole rung is well below the rate on its last dollar.
- 04
Enter the pre-tax balance available to convert and any other taxable income in a conversion year. The second one matters because a conversion is stacked on top of it when the marketplace credit is tested.
- 05
Check the statutory fields — the five-year clock, 59½, and under Advanced options the 10% penalty rate and the income where the marketplace credit ends — then read the headline: the taxable savings you need before rung one matures, and the year-by-year schedule underneath it.
Formula
Rungs = the number of conversions whose five-year wait still ends before the penalty age: ceil(59.5 − 5 − start age), so starting at 45 gives 10 rungs, converted at 45 through 54. Tax on each rung = the conversion × your effective rate, $60,000 × 12% = $7,200. Rung one becomes spendable at start age + 5. The page then asks, in every year from the first conversion until 59½, what has to come from outside the ladder: spending + that year's conversion tax − whatever rung matures that year. In the first five years nothing matures, so the answer is $60,000 + $7,200 = $67,200 a year and $336,000 in total, which is the headline. Once rungs start maturing, a $60,000 rung covers the $60,000 of spending but not the $7,200 of tax, so $7,200 a year keeps coming from outside until the conversions stop. Total from outside the ladder = the sum of those yearly shortfalls.
Example
Start at 45, $60,000 of spending, a $60,000 conversion each year at a 12% effective rate, $750,000 in the pre-tax account and no other taxable income. That is 10 rungs, converted at 45 through 54 — 54 is the last conversion that matures before 59½, so a conversion after it would unlock a door that is no longer locked. Each rung costs $7,200 of tax, $72,000 across the ladder, and $600,000 of the $750,000 gets converted, leaving $150,000 behind. Rung one becomes spendable at 50, so ages 45 to 49 have nothing maturing: $67,200 a year from taxable savings and $336,000 before the ladder carries anything at all. From 50 the maturing rung covers the spending but not the tax, so another $7,200 a year comes from outside until the last conversion at 54 — $372,000 from outside the ladder in total. The $60,000 conversion is also your income for the year: against the $62,600 where a single filer's marketplace credit ends, that leaves $2,600 of room, which is the real ceiling on rung size for anyone buying their own coverage.
Definitions
- Rung
- One year's conversion, with its own five-year clock. Rungs mature one a year in the order they were made, and each funds roughly a year of spending once it does.
- Conversion five-year clock
- The wait before a converted amount's principal can be withdrawn under 59½ without the 10% recapture penalty. It runs per conversion, from 1 January of the conversion year, and is irrelevant once you reach 59½.
- Ordering rules
- The fixed sequence in which money leaves a Roth IRA: contributions first, then conversions oldest-first, then earnings. It is why old contributions are reachable immediately and earnings are reachable last.
Good to know
The clock runs per conversion, not once for the ladder
This is the fact the whole page is built around, and the one most explanations blur. Each conversion carries its own five-year clock. The rung you convert at 45 is spendable at 50; the rung you convert at 46 is spendable at 51; nothing about the first conversion unlocks the second. There is no single clock that, once started, opens everything behind it — that describes a different rule entirely, the one governing whether Roth EARNINGS come out tax-free, which runs from your first Roth of any kind and is not what a ladder depends on. The consequence is structural, not a detail: a ladder has to start five years before the money is needed, and its first five years have nothing maturing at all. At the figures this page opens with, ages 45 through 49 need $60,000 of spending plus $7,200 of conversion tax every year, funded from somewhere that is not the ladder — $336,000 before the first rung carries anything. That number is the headline for a reason. A plan that budgets for the conversions but not for those five years is not a plan. The clock's edges are worth knowing exactly. It starts on 1 January of the tax year the conversion happens in, so a conversion made in December 2026 is available on 1 January 2031 — four years and one day later, which makes a late-December conversion materially better than an early-January one. It stops mattering at 59½: the 10% recapture penalty on conversion principal simply does not apply after that age, whatever any individual rung's clock says. Which is why the ladder has a natural last rung. Starting at 45, the tenth and final useful conversion is at 54, because a conversion at 55 matures at 60 — by which point the pre-tax account is open without a penalty anyway, and you would have paid tax years early to unlock a door that was no longer locked.
Paying the tax, and the ordering rules underneath everything
The most expensive mistake on a ladder is not sizing, it is withholding. Pay the tax on each conversion from money outside the retirement account — a bank account, a brokerage account, cash. Anything withheld from a pre-tax account to cover the tax never reaches the Roth: it is a distribution, so under 59½ it is taxed AND takes the 10% early-withdrawal penalty, and you finish taxed on more than actually converted. On a $60,000 rung at a 10% penalty rate, that is $6,000 of pure avoidable cost, repeated every year the mistake is repeated. A related practicality: conversions have no withholding by default, so the tax has to be paid through quarterly estimated payments or a safe-harbour adjustment somewhere else, or an underpayment penalty follows even when the total is eventually paid. The other set of rules to hold clearly are the ordering rules, which decide what any Roth withdrawal is made of. Money leaves a Roth IRA in a fixed sequence: contributions first, then conversions oldest-first, then earnings. Direct CONTRIBUTIONS come out at any time, at any age, with no clock, no tax and no penalty — they were never part of a ladder and never need to be, so anyone with a long-standing Roth already owns part of the bridge this page says the first five years need. CONVERSIONS come out next, each subject to its own five-year clock before 59½, oldest rung first, which is exactly the order a ladder wants. EARNINGS come out last and are the only part that needs both 59½ and the account's own five-year clock to be tax-free. All of this is tracked on Form 8606, filed for the year of each conversion. One more rule can ambush a ladder: if the traditional IRA being converted holds any nondeductible basis, the pro-rata rule treats every traditional, SEP and SIMPLE IRA you own as one pot and each conversion comes out part basis and part pre-tax. That does not stop a ladder, but it changes the taxable amount, and this page assumes a fully pre-tax balance.
Sizing a rung: two ceilings that fight each other
The rung and the year of spending it funds are separate fields on this page because they answer to different constraints. Pushing upward is bracket filling. A conversion year with no wages is the cheapest income most people will ever realise: the conversion stacks from the bottom of the rate schedule, the standard deduction absorbs the first slice entirely, and the low brackets absorb the next. That is why the tax field asks for an EFFECTIVE rate rather than a marginal one — the average rate across a whole $60,000 conversion is well below the rate on its last dollar. It also argues for converting more than you spend in the early years, because the marginal cost of the next slice is still small and every converted dollar is one that never faces a required distribution later. Pushing downward is the marketplace premium credit, and for anyone buying their own coverage it usually binds first. A conversion is ordinary income, and ordinary income is precisely what the credit is tested against. On 2026 figures the credit ends at $62,600 for a single filer and $84,600 for a household of two, and above that line it is zero rather than reduced — so the dollar that crosses costs the entire year's credit, often five figures, rather than its own tax. At the opening figures a $60,000 rung with no other income leaves just $2,600 of room. Other income stacks underneath: interest, dividends, a spouse's wages, a small pension all consume the headroom before the conversion does. There is a third, quieter constraint. A rung has to cover the spending it funds AND the tax on that year's conversion. A $60,000 rung against $60,000 of spending plus $7,200 of tax is $7,200 short every year, so the taxable account keeps being drawn on well past the first five years — $372,000 in total rather than $336,000. Converting slightly more than you spend closes that, at the cost of a little more income in a year where income is the scarce resource.
When to stop, and what a later conversion is actually for
A ladder has a definite end. Starting at 45 with a five-year clock and a penalty age of 59½, the last conversion worth making as a LADDER rung is at 54; anything later matures after the account has opened on its own. That does not mean conversions stop being useful at 54 — it means they stop being about access and start being about tax. The later case is a genuine one. Every dollar converted is a dollar that will never be a required minimum distribution, and RMDs begin at 73 (75 for those born in 1960 or later), often landing on a household whose spending has fallen and whose income is otherwise low. Conversions in the low-income years between retirement and 73 deliberately move income forward into cheap brackets and out of expensive ones. They also protect a surviving spouse, who will file as single on a bracket schedule roughly half as wide, and heirs, who must empty an inherited IRA within ten years — often during their own peak earning years. Set against that are three costs that get missed. Medicare's income-related surcharges look back two years, so a conversion at 63 raises the Part B and Part D premium at 65, and the surcharge is a cliff of its own rather than a taper. State income tax may apply to the conversion and varies enormously — some states do not tax retirement income at all, which makes the timing of a move a real planning variable. And growth on the pre-tax balance while the ladder runs, which this page does not model, means the account converts down more slowly than $600,000 out of $750,000 suggests. If the ladder simply cannot start five years before the money is needed, two alternatives cover the gap: a 72(t) series of substantially equal periodic payments, which is available at any age but locks you in for the later of five years or 59½, and the rule that lets you take from the plan of the employer you separated from in or after the year you turned 55 — which a rollover to an IRA destroys permanently.
Frequently asked questions
What is a Roth conversion ladder?
A way of getting at pre-tax retirement money before 59½ without the 10% penalty. Each year you convert a slice of a traditional 401(k) or IRA to a Roth IRA and pay ordinary income tax on it. Five years later that specific converted amount — the principal, not its earnings — can be withdrawn with no penalty and no further tax, whatever your age. Repeat annually and you build a staircase of amounts maturing one a year, each funding a year of spending.
Is the five-year clock one clock or one per conversion?
One per conversion, and this is the thing most explanations get wrong. The rung you convert at 45 is spendable at 50; the one you convert at 46 is spendable at 51. There is no single clock that, once started, unlocks everything behind it. That is why the ladder has to begin five years before the money is needed rather than the year it is needed, and why the first five years of it have nothing maturing at all.
When does a conversion's clock actually start and stop?
It starts on 1 January of the tax year the conversion happens in, so a conversion made in December 2026 is available on 1 January 2031 — four years and a day later, not five. It stops mattering entirely at 59½: after that age the recapture penalty on conversion principal no longer applies, whatever the clock says. A separate five-year clock governs whether Roth EARNINGS come out tax-free, and it runs from your first Roth contribution or conversion of any kind. Do not conflate the two.
How do I pay the tax on each rung?
From money outside the retirement account, always. Withholding tax out of the conversion itself means the withheld part never arrives in the Roth — it is a distribution, so under 59½ it is taxed and takes the 10% penalty on top, and you end up taxed on more than actually converted. On a $60,000 rung that is $6,000 of avoidable penalty. Pay it from a bank or brokerage account, and remember that a conversion has no withholding by default: you may need quarterly estimated payments or a safe-harbour adjustment to avoid an underpayment penalty.
How large should each rung be?
Two ceilings compete and the lower one wins. Upward, a conversion year with no wages is the cheapest income you will ever realise, so the classic move is to fill the low brackets deliberately — converting more than you spend, because the marginal cost of the next slice is still small. Downward, a conversion is ordinary income and ordinary income is what the marketplace premium credit is tested against: at $62,600 for a single filer or $84,600 for a household of two, the dollar that crosses the line costs the entire year's credit rather than its own tax. If you are buying your own coverage, the cliff is usually the binding constraint and it is well below the top of a low bracket.
What funds the years before the first rung matures?
Something outside the ladder, and it is the largest number on the page. At the opening figures, ages 45 to 49 need $67,200 a year — $60,000 of spending plus $7,200 of conversion tax — which is $336,000 before a single rung has matured. Usual sources: a taxable brokerage account, Roth CONTRIBUTIONS made in earlier years, which come out at any time at any age with no clock and no penalty, cash, or a 72(t) series. Roth contributions are the most-missed of those; the ordering rules take contributions out first, then conversions oldest-first, then earnings, so anyone with a long-standing Roth already has part of this bridge sitting there.