A Roth IRA conversion can be a smart tax move when the tax rate you pay on the conversion today is lower than the rate you reasonably expect to face on those dollars later. But the decision is not simply “Roth good, traditional bad.” The amount you convert can also affect Medicare premiums, ACA premium tax credits, capital-gain taxation, and your cash flow for paying the tax.
That is why I treat Roth IRA conversions as a yearly tax-planning decision, not a one-time retirement-account trick. The goal is to convert the right amount in the right year—not the biggest amount you can possibly move.
A Roth conversion moves money from a pre-tax retirement account into a Roth IRA. The untaxed portion you convert is generally included in your taxable income for that year, but future qualified Roth IRA withdrawals can be tax-free. A conversion tends to be more attractive when you have a temporary low-income year, expect higher taxable income later, want to reduce future required minimum distributions from pre-tax accounts, or value more tax flexibility in retirement. Before converting, model the income-tax cost plus Medicare’s income-related monthly adjustment amount (IRMAA), ACA premium-tax-credit effects, state taxes, capital gains, and how you will pay the tax.
Key Takeaways Ahead
Video: Roth Conversion Strategy for 2026
This video walks through the core planning idea: compare the tax cost of converting now with the tax cost and planning constraints you may face later. The article below updates the numbers and adds the 2026 tax, Medicare, and implementation details you need before acting.
How Roth IRA Conversions Work in 2026
A Roth conversion is a transfer of money from a traditional IRA or another eligible pre-tax retirement account to a Roth IRA. The IRS explains that untaxed amounts converted from a traditional IRA are generally taxable in the year of the conversion, and the conversion is reported on Form 8606.
The trade is straightforward: you voluntarily recognize taxable income today in exchange for moving those dollars into an account where future qualified distributions can be tax-free. Whether that trade is favorable depends on the tax rate you pay today, the tax rate you would otherwise pay later, and the other income-based costs the conversion triggers along the way.
- Choose the amount. Estimate your taxable income before the conversion and decide how much additional income you are willing to recognize.
- Execute the conversion. The IRS permits a trustee-to-trustee transfer, a same-trustee transfer, or a 60-day rollover. A direct transfer is usually simpler because you do not take possession of the money.
- Plan for the tax. The taxable portion of the conversion increases federal taxable income and may also affect state income tax.
- Keep the records. Form 8606 is used to report traditional-to-Roth IRA conversions and is especially important when you have nondeductible IRA basis.
A 2026 Bracket-Filling Example
Assume a married couple filing jointly expects $150,000 of taxable income in 2026 before any Roth conversion. Under the IRS 2026 tax brackets, the 22% bracket runs through $211,400 of taxable income for married couples filing jointly.
That means this couple has $61,400 of room before taxable income enters the 24% bracket. A $50,000 conversion would keep the example inside the 22% bracket and create roughly $11,000 of additional federal income tax from the conversion itself, before considering credits, capital gains, state taxes, Medicare, ACA effects, or other items on the return.
“I can convert $61,400 before the next bracket” does not mean “I should convert $61,400.” Tax brackets are only one constraint. A conversion can change the tax rate on capital gains, reduce an ACA premium tax credit, increase future Medicare IRMAA, or create a cash-flow problem if you do not have outside money available for the tax.
If you are under age 59½ or expect to use Roth money soon, the tax decision and the withdrawal decision are separate. Roth IRA distribution ordering and the conversion five-year periods can change whether an early distribution is subject to the 10% additional tax. See the current guide to Roth IRA five-year rules before treating converted dollars as immediately spendable.
When a Roth Conversion May Be Worth It
The strongest Roth conversion opportunities usually come from a mismatch between your tax rate now and your likely tax rate later. The mistake is assuming that “later” automatically means higher. Sometimes it will. Sometimes it will not.
I would start with five questions:
- Is this an unusually low-income year? Retirement before Social Security or RMDs, a sabbatical, job loss, a business-loss year, or a large deduction can create temporary tax capacity.
- Will future pre-tax withdrawals be larger than you need? Large traditional IRA and 401(k) balances can eventually create required distributions that reduce your control over taxable income.
- Could the surviving spouse face a higher tax rate? A married couple may eventually become a single filer while still owning much of the same retirement wealth.
- Can you pay the conversion tax without raiding the converted money? Outside cash often makes the economics cleaner because more of the retirement money remains invested in the Roth.
- What else moves when modified adjusted gross income (MAGI) moves? Medicare IRMAA, ACA premium tax credits, capital-gain taxation, and other income-sensitive items can matter as much as the next ordinary-income bracket.
The best Roth conversion year is often not the year with the lowest tax bracket on paper. It is the year when the whole tax system gives you the most room. A conversion that “fits” inside a bracket can still be expensive if it pushes another part of your return over a threshold.
This is the part that real-world planning software sometimes hides behind a single “optimal conversion” number. The number is only as good as the assumptions underneath it. Current tax rates are knowable; your future tax law, investment returns, spending, marital status, and longevity are not. I would rather use a reasonable range and revisit it each year than pretend a 25-year projection can identify the perfect dollar amount today.
For Medicare-age households, remember the timing lag. A Roth conversion increases MAGI in the conversion year. Social Security generally uses tax-return information from two years earlier to determine IRMAA, so a 2026 conversion can affect 2028 Medicare premiums. The 2028 IRMAA thresholds are not known yet. By contrast, the official 2026 IRMAA thresholds are $109,000 for single filers and $218,000 for joint filers and are based on earlier-year income.
If IRMAA is close enough to change the decision, do not guess from this year’s threshold. Use the dedicated method for estimating how much Roth conversion room you have before IRMAA, then compare the extra Medicare cost with the long-term tax benefit rather than treating IRMAA as an automatic stop sign.
The useful Roth conversion question is rarely just “What bracket am I in?” Each week I break down one practical money decision like this—the hidden threshold, the tradeoff that changes the answer, and what I would check before acting.
- Spot the income thresholds that can quietly change a conversion’s real cost.
- See when a low-income year is actually a planning opportunity.
- Turn complicated retirement-tax rules into a short decision checklist.
The CONVERT Framework for Choosing a Conversion Amount
The seven-step CONVERT Framework turns the decision into a sequence: establish the tax-rate case first, then test the interactions that can overturn it.
Use these seven checks before setting a Roth conversion amount.
When I Would Slow Down or Skip a Conversion
A Roth conversion is not a prize you win by doing more of it. I would be cautious when the conversion pushes dollars into a materially higher current tax rate, destroys an ACA subsidy, creates an unattractive IRMAA tradeoff, forces you to use retirement money to pay the tax, or when you reasonably expect to withdraw the traditional IRA dollars later at a lower rate.
I would also slow down when the plan depends on one heroic assumption—such as future tax rates definitely doubling or an investment return projection making the conversion “pay for itself.” A conversion changes the tax character of money. It does not create investment return by itself.
The Pro-Rata Rule and Backdoor Roth Conversions
The pro-rata rule matters most when you have made nondeductible traditional IRA contributions and are trying to convert after-tax basis while other pre-tax IRA money still exists. For Form 8606 purposes, traditional, SEP, and SIMPLE IRA balances are generally considered together rather than letting you select only the after-tax dollars and label that piece tax-free.
One possible planning technique is a reverse rollover. IRS Publication 590-A explains that the otherwise-taxable portion of a traditional IRA distribution may be rolled into an eligible employer plan if that plan accepts the rollover, while basis can remain in the IRA. Employer-plan terms control whether that rollover is available, and the timing and tax reporting need to be checked before using the technique.
The important distinction is that this is a basis-management issue, not the core Roth conversion decision covered by this page. If you have after-tax IRA basis, use the IRS Form 8606 guidance and verify the transaction with your tax professional or plan administrator before assuming a rollover eliminates the taxable portion of a conversion.
Roth Conversion Decision Calculator
Use the calculator to compare the estimated upfront tax cost of a conversion with the long-term Roth-versus-traditional outcome under your assumptions. Treat the result as a planning range, not a command. The inputs that deserve the most scrutiny are your current marginal rate, expected future rate, time horizon, investment return assumption, state tax, and any ACA or Medicare cost you add to the current-year conversion.
If the decision is close, run more than one scenario. I would rather see a “convert $30,000–$50,000 depending on year-end income” range than a model that spits out $43,712 and pretends the future is that precise.
You can also compare the calculator result with the dedicated Roth conversion calculator guide if you want a deeper explanation of the assumptions.
Roth Decision Calculator
Compare a Roth conversion with leaving money pre-tax, including the potential effect of Marketplace premium-tax-credit changes, or compare recurring Roth and Traditional IRA contributions.
Roth Decision Comparison
ACA Marketplace comparison
| ACA household MAGI before conversion | |
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| ACA household MAGI after conversion | |
| Advance credits received | |
| Estimated reconciliation without conversion | |
| Estimated reconciliation with conversion | |
| Additional ACA cost caused by conversion |
What is driving this result
Important planning checks
Roth Decisions Are Tax-Timing Decisions
Get independent financial education about Roth conversions, retirement tax brackets, ACA subsidies, RMDs, Medicare IRMAA, and coordinating withdrawals over time.
Roth Conversion FAQs
The Bottom Line on Roth IRA Conversions
A Roth conversion is worth considering when paying tax today buys you meaningful tax flexibility later at a reasonable total cost. The decision gets weaker when the conversion merely accelerates tax into a higher-rate year or creates larger side costs than the future tax problem you are trying to solve.
My decision rule is simple: compare rates, then test thresholds, then choose an amount you can defend without pretending you know the future. If the answer still looks good after Medicare, ACA, capital gains, state tax, liquidity, and withdrawal timing are included, you have a real Roth conversion case—not just a tax-bracket story.
- Estimate your 2026 taxable income before the conversion.
- Model a small, medium, and large conversion rather than one “perfect” amount.
- Check Medicare, ACA, capital gains, state tax, and the source of the tax payment.
- Recheck the numbers near year-end before completing the final conversion.
Sources
- IRS: Retirement Plans FAQs Regarding IRAs
- IRS: 2026 Tax Inflation Adjustments
- IRS: Form 8606, Nondeductible IRAs
- IRS Publication 590-B: Distributions from IRAs
- IRS Publication 590-A: Contributions and IRA Rollovers
- IRS: Premium Tax Credit Questions and Answers
- CMS: 2026 Medicare Part B Premiums and IRMAA
Educational use only: Roth conversions can affect federal and state income taxes, Medicare premiums, health-insurance subsidies, and retirement-account withdrawal planning. This article provides general education, not individualized tax, legal, or investment advice. Verify current rules and your own return with a qualified tax professional or financial professional before executing a material conversion.
