A Roth conversion is worth doing when the tax you pay on the converted money now is lower than the tax you or your heirs would pay on it later. So the question isn’t really whether to convert. It’s how much to convert this year, which means knowing exactly where your income sits against the tax brackets, the Medicare premium lines and, before 65, your health insurance credit. For a married couple in 2026, the 12% bracket runs to $100,800 of taxable income and the 22% bracket to $211,400, and those two lines decide most conversion plans.
The decision in one sentence
Each year, you choose an amount to move from a traditional IRA or 401(k) into a Roth, add it to your income, and pay the tax. Convert too little and later required minimum distributions may push you into a higher bracket for the rest of your life. Convert too much in one year and you pay a higher rate now, and possibly higher Medicare premiums, for no gain. The glossary entry covers the basic rules; this page is about sizing the amount.
The lines that set the amount
Your tax bracket
The 2026 brackets apply to taxable income, after the standard deduction of $32,200 for a married couple or $16,100 for a single filer.
For single filers the same brackets end at about half these amounts: $50,400 for 12% and $105,700 for 22%. These are the same seven rates as in 2025, from 10% to 37%, so the old argument that rates were due to rise in 2026 no longer applies. The case for converting now has to rest on your own numbers.
Medicare premiums, two years later
In 2026 the standard Part B premium is $202.90 a month. Once modified adjusted gross income passes $218,000 on a joint return ($109,000 single), it jumps to $284.10 each, and keeps stepping up from there. The income counted is from two years earlier, so a conversion at 63 can raise premiums at 65. A dollar of conversion over the line costs the whole step, so good plans stop just under it.
Social Security taxes
If you’re already collecting Social Security, conversion income can make more of your benefit taxable. Up to 85% of benefits become taxable once half your benefits plus other income passes $44,000 for a married couple or $34,000 for a single filer. That pushes the real rate on some conversion dollars above your bracket. It’s one reason many people convert before claiming. See when to claim Social Security.
Health insurance before 65
If you buy coverage through the Marketplace, conversion income counts toward the income that sets your premium tax credit, and so do most IRA withdrawals. Above the credit’s income limit you can lose the credit entirely. See health insurance if you retire early before converting in those years.
A worked example
A married couple, both 64, retired, with $60,000 of other income in 2026. After the $32,200 standard deduction, their taxable income is $27,800.
- Filling the 12% bracket takes a $73,000 conversion, taxed at 12%: $8,760.
- Going on to just under the first Medicare line ($218,000 of income, the level that sets their premiums at 66) adds $85,000 more at 22%: $18,700.
- Total: $158,000 converted for $27,460 of federal tax, an average of about 17%.
Converting another $25,600 to reach the top of the 22% bracket would cost 22% plus the first Medicare premium step for both of them in 2028. Whether the $158,000 is right depends on what rate that money would face later, which is the part a planner projects. This example uses 2026 federal brackets and the standard deduction only; it leaves out state tax, credits and the extra deductions at 65.
Common mistakes
- Paying the tax from the IRA. It shrinks what ends up in the Roth, and before 59½ the withheld amount counts as a withdrawal.
- Converting before the year’s income is known. A conversion can’t be undone. Many planners do the bulk in November or December, once bonuses, capital gains and fund distributions are clear.
- Missing the estimated tax. A large conversion can trigger an underpayment penalty. You avoid it if withholding and estimated payments cover 100% of last year’s tax (110% if last year’s adjusted gross income was over $150,000) or 90% of this year’s.
- Converting money you plan to give away. If an IRA will go to charity, through qualified charitable distributions from 70½ or at death, it may never be taxed. Converting it pays tax that didn’t need paying.
- Ignoring who inherits. Most heirs other than a spouse must empty an inherited IRA within 10 years. If they’ll be in their peak earning years, converting at your lower rate can save the family tax. If they’ll be in a low bracket, it may not.
- Forgetting state tax. Moving to a state with no income tax next year can make waiting the better choice.
Questions to ask an advisor
| Ask | A good answer includes |
|---|---|
| How much would you convert this year, and why that amount? | A dollar figure tied to a bracket or premium line |
| What rate do you expect this money to face if I don’t convert? | A projection of your future required distributions and bracket |
| What does this do to my Medicare premiums or health insurance credit? | The income line for each, and your distance from it |
| Where does the tax money come from? | Cash or a taxable account, not the IRA |
| How are you paid, in dollars a year? | One figure; no commission tied to what you buy with the money |
When an advisor is worth it, and what it costs
A planner earns their fee here when your pre-tax balance is large enough that future distributions will matter, when you have a window of low-income years between retiring and 73, or when Social Security, Medicare or Marketplace credits interact with the amount. If your balance is small or your income will stay level, the answer may be simple enough to work out yourself.
A conversion plan is mostly a tax projection, so it fits a one-time plan (median $2,000, middle half $845 to $3,600) or a few hours at a median $300. If you’ll convert every year for five or ten years, ongoing planning at a median $4,500 a year re-runs the numbers each fall when the year’s income is known. Ask whether the planner prepares or reviews the tax return, because the conversion is reported on Form 8606.
An advisor paid a percentage of assets is paid the same whether you convert or not, which is fine. What matters is that they show the projection, not just a recommendation.
How to find one
Start with the tax planning specialty, where advisors list multi-year tax strategy, or the retirement planning specialists. The best conversion years usually come just before or just after retiring, so the lists of advisors for pre-retirees and retirees are a good place to look, along with everyone who serves pre-retirees. For the wider retirement picture, see what to look for in a retirement advisor.