The cost of waiting to do a Roth conversion is the tax-free growth and low-bracket room you surrender each year you delay, plus the higher rates your required minimum distributions can force later. For retired investors in their gap years (retired but not yet taking RMDs), every skipped year narrows a planning window that permanently closes at age 73 or 75.
Waiting to convert leaves dollars in a traditional IRA, where they keep growing with an embedded, growing tax bill. Each delayed year removes one low-income gap year (roughly age 60 to 73) that you cannot get back, and it moves you closer to RMDs at 73 or 75, when required income fills your lower brackets and conversion room shrinks.
What does waiting on a Roth conversion actually cost you?
The cost of waiting to do a Roth conversion has three parts: forgone tax-free compounding inside a Roth, the loss of a low-bracket gap year that never returns, and a larger future balance that RMDs may tax at a higher rate. Because your conversion window closes at RMD age (73 or 75), delay both raises the eventual tax and shortens the runway to spread it.
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Many pre-retirees and retired “IRA millionaires” tell themselves they will convert “sometime this year” or “next year.” The problem with that framing is that a Roth conversion window is finite. It opens when your wages stop and closes when required minimum distributions begin. Each year inside that window is a low-income year with room to convert at a known rate. Skip one, and you do not get to add it back at the end.
The table below shows how the same decision changes as delay stretches out. It is a directional illustration, not a promised result, but the pattern holds across most gap-year households.
| If you delay a Roth conversion | What changes on the board | Illustrative effect |
|---|---|---|
| By 1 year | Balance keeps compounding pre-tax; one fewer year of tax-free Roth growth | Larger future taxable balance; one gap year lost for good |
| By 5 years | Five fewer gap years; RMDs are closer; bracket-fill room may shrink | Remaining conversions may crowd into higher brackets and IRMAA tiers |
| Until RMDs begin (73 or 75) | Window closes; RMDs become mandatory taxable income and cannot be converted | You convert (or withdraw) on the IRS calendar at RMD-inflated rates |
This page takes the timing angle: when your window is open and what closing it early costs. For a plain-dollars look at the same problem, see our companion explainer on why waiting on your Roth conversion costs you real money.
Why is a Roth conversion five moves, not one?
A Roth conversion is closer to a chess game against the IRS than a single December transaction. Five people or roles have to be positioned before a well-timed move is possible: your CPA, your investment advisor, your estate attorney, your spouse, and the timing itself. Each has its own lead time, so a plan built in the last weeks of the year rarely comes together well.
Households that treat a conversion as one afternoon of clicking buttons tend to leave value on the table. Households that treat it as a set of coordinated moves, each started early, often do better over a lifetime. Here is how the five pieces line up.
The Rook: why does your CPA need lead time before tax season?
Your CPA is the rook: powerful once the board opens, but stuck behind other pieces early on. From February through April they are buried in filings and extensions. To coordinate estimated payments, withholding, and conversion sizing well, that conversation often needs to happen between filings, not during them. Miss that window and the coordination can slip into the following year, costing you a gap year of runway.
The Bishop: what should you convert, not just how much?
Your investment advisor is the bishop, working the diagonal lines many people miss. Most households ask how much to convert. A related question is what to convert: which specific holdings are temporarily down, which may fit a recovery timeline, and which suit the overall portfolio. Answering that well takes time, not the last three weeks of December. Our guide on how much to convert to a Roth walks through sizing the amount.
The Knight: how can a conversion break your estate plan?
Your estate attorney is the knight: the piece that jumps and surprises you. Converting from a traditional IRA to a Roth changes the tax character of those dollars from pre-tax to post-tax, and that can ripple into how the account passes to heirs, how it interacts with existing trusts, and whether your current documents do what you think. A short review before a large conversion sequence can keep the plan from breaking something else.
The King: why must your spouse be in the room?
Your spouse is the king, the piece the whole strategy protects. Conversion planning affects both retirements and, importantly, the survivor after the first spouse passes, including exposure to single-filer brackets, IRMAA thresholds, and forced RMD income. A plan can look strong on paper and still stall if the person most affected by the long-term consequences is not an active part of the decision.
The Queen: how does timing shape a conversion?
Timing is the queen, a flexible piece, but only when it has room to move. A useful conversion opportunity rarely arrives in December. It can appear when markets dip, when projected income comes in lower than expected, or when a mid-year tax projection reveals unused bracket room. Spotting those moments takes a full year of monitoring. A conversion is irreversible and must be completed by the December 31 deadline, so late-year starts leave little margin.
When is your Roth conversion window, and why do the gap years matter?
Your conversion window is the gap years: the stretch between the year you retire and the year RMDs begin at age 73 (born 1951 to 1959) or 75 (born 1960 or later, first affected in 2035). Many retirees have a 5 to 12 year window of low-income years. Each one lets you convert at a known, often lower rate before required withdrawals fill your brackets.
Once you stop working, your taxable income often drops before Social Security and RMDs kick in. That valley is the opening. You can fill your current bracket on purpose, converting up to a ceiling you choose rather than one the IRS forces on you later. In 2026 the 24% bracket runs up to $201,775 for single filers and $403,550 for married couples filing jointly, a common target ceiling for gap-year conversions.
Today’s rates are the current-law baseline, not a temporary discount. The One Big Beautiful Bill Act (P.L. 119-21), signed in July 2025, made the 2017 Tax Cuts and Jobs Act individual brackets permanent, so the 10 to 37 percent schedule no longer faces the sunset that had been set for the end of 2025. That removes one guessing game, but it does not remove the case for acting during your gap years: your own effective rate can still climb as RMDs and Social Security stack income into higher brackets, and a future Congress can revisit the law again.
Two other ceilings usually matter more than the next bracket line:
- IRMAA (Medicare surcharges). In 2026 the standard Medicare Part B premium is $202.90 per month, and income-related surcharges begin above $109,000 MAGI for single filers and $218,000 for joint filers. IRMAA uses a 2-year lookback, so a conversion at age 63 can raise premiums at 65. Age 62 is the last conversion year that does not affect a Medicare premium.
- Social Security taxability. As conversion income rises, a larger share of your Social Security benefits (up to 85%) can become taxable, which is another reason to convert in the years before benefits and RMDs stack on top.
The window is real and it closes. When RMDs start, that required income lands on your return every year, you cannot convert an RMD, and the low-bracket room you had is now occupied. See our 2026 overview of required minimum distributions for the start-age rules. One helpful note: a conversion is taxable ordinary income but is not itself net investment income, so it does not directly trigger the 3.8% net investment income tax (NIIT), though it can raise MAGI enough to expose other investment income.
How much does waiting one year vs. five years really cost?
Waiting trades a tax rate you can see today for an unknown rate later, applied to a balance that has kept growing. A conversion is taxable ordinary income: convert $100,000 at a 24% marginal rate and the tax is about $24,000 for that year. Left in a traditional IRA, those dollars and their future growth stay fully taxable whenever they eventually come out, often as required income after RMDs begin.
The core of the break-even question is straightforward: pay a rate you can see now, or pay an unknown rate later on money that has grown. Which path leaves more after tax depends on your current bracket, your projected bracket once RMDs begin, how long the balance would keep compounding, and whether the later withdrawal pushes into higher brackets or IRMAA tiers.
The compounding side of the question often points toward starting earlier, because dollars moved into a Roth grow without an embedded future tax, while the same dollars left in a traditional IRA carry a tax on each future gain. Where the two paths cross depends on your own rates and time horizon. To model that crossover for your situation, see our walkthrough of the Roth conversion break-even analysis. These are illustrations, not forecasts, and individual results vary.
Why does compounding now work against you?
Most IRA millionaires built wealth through compounding, but inside a traditional IRA that same force now works against them. Every dollar of growth is another dollar the IRS eventually taxes at ordinary rates. The longer the balance sits, the larger the government’s embedded claim grows, and the more RMD income it can force into higher brackets once withdrawals begin.
The account statement can be misleading. A traditional IRA balance is not all spendable money; a meaningful slice is a deferred tax bill that grows right along with the account. The only open questions are when that tax gets paid and on what amount. While you wait, the balance keeps rising, and so does the amount subject to tax.
That is why compounding cuts both ways. It built the balance, and now it inflates the future tax on that balance. Converting during the gap years lets you move dollars from the taxed-later side of the ledger to the never-taxed-again side while your rate is still under your control.
What are the most common Roth conversion timing mistakes?
The most common timing mistakes all shrink the window: treating conversions as a December task, delaying the CPA and spouse conversations, waiting for markets to “feel safe,” and confusing having a plan with executing one. Each error quietly moves you closer to RMD age with fewer low-bracket years left to work with.
- Treating conversion as a December transaction. A coordinated plan needs a full year of runway. The last six weeks rarely give all five pieces time to move.
- Delaying the CPA conversation until next tax season. The workable time to coordinate is between filings, while the rook can actually move.
- Postponing the spouse conversation. Plans stall most often when the king is not in the room. Genuine alignment early tends to matter more than perfect math later.
- Waiting for markets to feel certain. They rarely do. Down markets can be useful conversion moments because you convert more shares at a lower taxable value.
- Confusing “I have a plan” with “I have a result.” A plan in a folder does not lower taxes; only completed conversions do.
Work with Q3 Advisors
Q3 Advisors is a registered investment adviser focused on retirement tax planning. This page is educational and is not advice; consult a qualified professional.
Frequently asked questions
What is the best age to do a Roth conversion?
Many investors find the gap years (roughly age 60 to 73) particularly useful, after wages stop and before RMDs and Social Security fill the brackets. There is no single best age; it depends on income, IRA balance, and bracket room. The window often opens at retirement and closes when RMDs begin at 73 or 75.
Is there a downside to waiting to do a Roth conversion?
Yes. Waiting keeps dollars in a traditional IRA, where they grow with an embedded, growing tax bill, shortens the low-bracket gap-year window, and can push conversions into higher brackets once RMDs begin at 73 or 75. Delay can also raise future IRMAA Medicare surcharges (above $109,000 single or $218,000 joint MAGI in 2026) and increase the taxable share of Social Security.
At what age does a Roth conversion no longer make sense?
There is no hard cutoff, but conversions often become less useful once RMDs begin at 73 or 75, because you cannot convert an RMD and the required withdrawal already fills your lower brackets. The 2-year IRMAA lookback also matters: a conversion at 63 or later can raise Medicare premiums, and age 62 is the last conversion year that does not affect a premium.
Should I do a Roth conversion before RMDs start?
Many retirees consider it. Before RMDs begin at 73 or 75, gap-year income is often low, which can leave bracket room to convert at a known rate. Once RMDs start, that required income fills the lower brackets and you cannot convert an RMD, so the pre-RMD years are frequently when conversion room is available and delay tends to add to the eventual tax.
How much tax will I pay if I convert to a Roth?
A conversion is taxable ordinary income at your marginal rate for the year. In 2026 that ranges from 10% to 37%; the 24% bracket runs to $201,775 single and $403,550 for married couples filing jointly. The converted amount stacks on top of your other income, so the rate depends on how much you convert and your total taxable income for the year.
What is the 5-year rule for a Roth conversion?
Each Roth conversion starts its own 5-year clock. To withdraw converted principal without a 10% penalty, you generally must wait 5 years or reach age 59.5. A separate 5-year rule governs tax-free earnings. Because each conversion carries its own clock, converting earlier in your gap years starts these periods sooner and adds flexibility later.
