# How much to convert to Roth without hitting IRMAA

By James Ustby, CFP®, APMA®. Published 2026-10-24. Canonical URL: https://jamesustby.com/articles/roth-conversion-irmaa-how-much

> A 2026 Roth conversion sets your 2028 Medicare premiums. The worked example shows how to size one under the $218,000 joint IRMAA line, with tax.

## Key takeaways

- Medicare's income surcharge, IRMAA, usually reads your tax return from two years earlier, so a Roth conversion done in 2026 can raise Medicare premiums in 2028.
- For 2026, married couples filing jointly pay no IRMAA with modified adjusted gross income of $218,000 or less. One dollar over moves both spouses into the first tier.
- The tiers are cliffs. In our hypothetical, converting $149,000 instead of $148,000 adds about $220 of federal tax and about $2,297 of Medicare surcharges for the couple, using 2026 amounts.
- Tax-exempt interest counts toward the Medicare income test, so municipal bond income shrinks the room for a conversion.
- On October 23, 2026, the IRS urged taxpayers to check withholding and estimated tax payments now, ahead of the 2027 filing season. A conversion adds income, and how much tax comes out of it depends on the withholding election you make.

## The short answer

To avoid IRMAA, size a 2026 Roth conversion so your modified adjusted gross income (MAGI) stays at or under the Medicare line: $218,000 for a married couple filing jointly, or $109,000 for other filers, using 2026 figures. Start from that line, subtract your other income, including tax-exempt interest, and leave a cushion.

IRMAA (the income-related monthly adjustment amount) is the extra premium Medicare charges higher-income people for Part B and Part D. Because it looks back two years, the conversion you make this December can set what you pay for Medicare in 2028.

## Why does the IRS reminder this week matter for a Roth conversion?

On October 23, 2026, the IRS issued [IR-2026-128](https://www.irs.gov/newsroom/irs-reminder-year-round-tax-planning-can-make-filing-easier), a reminder to plan now and avoid surprises at tax time. It asks taxpayers to check withholding and estimated tax payments, and it singles out people whose income is not subject to withholding, including small business owners and the self-employed.

A Roth conversion often works the same way. When you move money from a traditional IRA to a Roth IRA, the IRS says the conversion "results in taxation of any untaxed amounts in the traditional IRA," and you report it on Form 8606 ([IRS IRA FAQs](https://www.irs.gov/retirement-plans/retirement-plans-faqs-regarding-iras)). How much tax, if any, is withheld depends on the election you make on the custodian's form. And the decision has a deadline: a conversion counts in the tax year the money leaves the traditional IRA, so a 2026 conversion has to be finished by December 31, 2026.

That makes late October a natural time to size the number. Most of your 2026 income is known, and there is still time to act.

## How does IRMAA work, and why is it a cliff?

Social Security sets IRMAA from your MAGI, which for this purpose is adjusted gross income plus tax-exempt interest. It uses the most recent return the IRS can provide, generally from two years before the premium year ([SSA POMS HI 01101.010](https://secure.ssa.gov/POMS.nsf/lnx/0601101010)). So 2026 premiums use 2024 returns, and a 2026 conversion generally lands in 2028 premiums. Our Nest Egg letter on [the Medicare IRMAA two-year lookback](https://jamesustby.com/articles/nest-egg-medicare-irmaa-two-year-lookback) walks through that timing.

These are the 2026 tiers for joint filers, with the surcharge each person on Medicare pays on top of the standard Part B premium of $202.90 and their drug plan premium ([CMS](https://www.cms.gov/newsroom/fact-sheets/2026-medicare-parts-b-premiums-deductibles)):

| 2026 joint MAGI | Part B surcharge per month | Part D surcharge per month | Extra per person per year |
|---|---|---|---|
| $218,000 or less | $0.00 | $0.00 | $0 |
| Over $218,000 to $274,000 | $81.20 | $14.50 | $1,148.40 |
| Over $274,000 to $342,000 | $202.90 | $37.50 | $2,884.80 |
| Over $342,000 to $410,000 | $324.60 | $60.40 | $4,620.00 |
| Over $410,000 and under $750,000 | $446.30 | $83.30 | $6,355.20 |
| $750,000 or more | $487.00 | $91.00 | $6,936.00 |

Single filers have their own 2026 lines: the tiers start above $109,000, $137,000, $171,000 and $205,000, and the top tier starts at $500,000. The tiers are not phased in. One dollar over a line puts you in the whole tier for the year, and on a joint return both spouses on Medicare pay it.

One honest limit: the tables that will apply to 2028 premiums do not exist yet. CMS publishes each year's amounts in the fall before the year starts, and Social Security raises the income lines with inflation (the first joint line went from $194,000 for 2023 to $218,000 for 2026, per the POMS table). Planning against the 2026 lines, as below, is a working assumption, not a forecast.

## How much can you convert? A worked example

Hypothetical example. Rick and Dana are both 64 and file jointly. Rick sold his company in 2025 and neither of them works now. In 2026 they have $62,000 of taxable interest from the sale proceeds and $8,000 of tax-exempt municipal bond interest. Rick has $1,500,000 in a traditional IRA that he rolled over from the company 401(k). They will both turn 65 in 2027 and be on Medicare all of 2028, so their 2026 return will likely set their 2028 premiums.

Their starting MAGI is $70,000 ($62,000 plus the $8,000 of tax-exempt interest). The room under the first IRMAA line is $218,000 minus $70,000, or $148,000.

Here is what different conversion sizes would do, using 2026 federal brackets and the $32,200 standard deduction for joint filers ([IRS, Rev. Proc. 2025-32](https://www.irs.gov/newsroom/irs-releases-tax-inflation-adjustments-for-tax-year-2026-including-amendments-from-the-one-big-beautiful-bill)) and the 2026 IRMAA amounts above for both spouses:

| Conversion | MAGI | Taxable income | Federal income tax and NIIT from the conversion | Top bracket | Extra Medicare cost for the couple (one year) |
|---|---|---|---|---|---|
| $100,000 | $170,000 | $129,800 | $14,900 | 22% | $0 |
| $148,000 | $218,000 | $177,800 | $25,460 | 22% | $0 |
| $149,000 | $219,000 | $178,800 | $25,680 | 22% | $2,296.80 |
| $204,000 | $274,000 | $233,800 | $38,836 | 24% | $2,296.80 |
| $272,000 | $342,000 | $301,800 | $56,904 | 24% | $5,769.60 |

Look at the second and third rows. The last $1,000 of conversion adds about $220 of federal tax and $2,296.80 of Medicare surcharges for the year, about $2,517 in all. That is the cliff.

Look at the fourth row too. Once you are past a line, the next line is the one that matters. Converting $204,000 costs the same IRMAA as converting $149,000, so if Rick and Dana decide one tier is worth paying, the top of that tier is the natural stopping point. The $55,000 between the third and fourth rows adds $13,156 of federal tax, about 24%, and no more IRMAA. Part of that stretch costs a little more: for Rick and Dana, the net investment income tax starts once the conversion passes $188,000, so the last $16,000 costs 27.8% instead of 24%. Whether it is worth paying depends on what the Roth money is for, their tax rates later, and how long the surcharge lasts, which is one year per year of high income.

Rows four and five include the 3.8% net investment income tax, which applies to the lesser of investment income or the amount by which modified adjusted gross income passes $250,000 on a joint return ([IRS](https://www.irs.gov/individuals/net-investment-income-tax)). The conversion is not investment income, but it raises that income figure, so $608 and $2,356 of the tax land on Rick and Dana's interest. (For this tax, modified adjusted gross income leaves out the $8,000 of tax-exempt interest, so it is $8,000 below the MAGI column.) This example leaves out state tax, assumes no other deductions or credits, and assumes both spouses have Part B and Part D all of 2028.

## Why does a business sale change the math?

Owners often get a window between the sale and the start of required minimum distributions when taxable income is unusually low. That window is when many people look at Roth conversions. Two things make it tighter than it looks.

First, the sale year itself. A large gain can push MAGI far above every IRMAA line, and that return will set Medicare premiums two years later. If you are 63 or older in the sale year, plan for it. Our article on [taxes on a business sale](https://jamesustby.com/articles/selling-my-business-tax-implications) walks through the pieces of that bill, and [what to do after selling a business](https://jamesustby.com/articles/what-to-do-after-selling-business) covers the first decisions once the money lands.

Second, where the proceeds are invested. Interest, dividends and capital gains from the proceeds all count toward MAGI, and so does tax-exempt bond interest. In the example, $8,000 of municipal interest cost Rick and Dana $8,000 of conversion room.

The free [IRMAA calculator](https://jamesustby.com/irmaa-calculator) shows which 2026 tier a MAGI figure falls in and what it costs per year.

## What should you check before you convert this year?

1. **Add up 2026 income so far.** Wages, interest, dividends, capital gains distributions, and tax-exempt interest. Year-end fund distributions can arrive in December.
2. **Pick the line you are aiming under.** The first IRMAA line, the top of a tier you are willing to pay, or the top of a tax bracket, whichever comes first.
3. **Leave a cushion.** A dollar over costs the whole tier, and a conversion cannot be undone. Since January 1, 2018, a conversion to a Roth IRA cannot be recharacterized ([IRS IRA FAQs](https://www.irs.gov/retirement-plans/retirement-plans-faqs-regarding-iras)).
4. **Plan the tax payment.** Decide whether to have tax withheld or to make an estimated payment. The IRS says you may owe a penalty if you do not pay enough through withholding and estimated tax during the year ([IRS, Estimated taxes](https://www.irs.gov/businesses/small-businesses-self-employed/estimated-taxes)).
5. **Know what an appeal can and cannot do.** Form SSA-44 lets you ask Social Security for a lower IRMAA after a life-changing event that reduced income, such as marriage, divorce, the death of a spouse, loss of income or an employer settlement payment ([SSA](https://www.ssa.gov/medicare/lower-irmaa)). A conversion you chose to make is not on that list.

If you want the full method, James's book [*The Roth Conversion Decision*](https://www.amazon.com/dp/B0HP1V77HG) (Kindle and paperback on Amazon) has free printable worksheets on its [Roth conversion page](https://jamesustby.com/roth-conversion). [*Medicare IRMAA, Explained*](https://www.amazon.com/dp/B0HMZD8PP2) covers the tiers and the SSA-44 process. Both are on the [books page](https://jamesustby.com/books). Consult your tax advisor about your own return before you convert.

## The bottom line

A Roth conversion in 2026 is taxed in 2026, and it can raise Medicare premiums in 2028. For a couple filing jointly, the first IRMAA line is $218,000 of MAGI using 2026 figures, and tax-exempt interest counts toward it. In our hypothetical, a $148,000 conversion stayed under the line, and a $149,000 conversion cost about $2,297 more in Medicare surcharges for one year. Size the number after you know the rest of your income, leave a cushion, and plan how the tax gets paid.

What is your MAGI for 2026 so far, and how much room does it leave under the line you care about?

## Next steps if you own a business

- **Get the next one by email.** [The Liquidity Letter](#ll-foot-title) covers exits, cash and taxes for owners with millions on the line. Sign up in the box at the bottom of this page.
- **Check your tier.** The free [IRMAA calculator](https://jamesustby.com/irmaa-calculator) shows which 2026 tier a MAGI figure lands in and what it costs per year.
- **Talk it through.** If you sold, or plan to, and want to size a conversion against your own numbers, [book a free call](https://oncehub.com/jamesustby).

## Questions people ask next

### Does a Roth conversion count as income for IRMAA?

Yes. The converted amount is taxable income that raises adjusted gross income, and IRMAA uses adjusted gross income plus tax-exempt interest. A conversion in 2026 generally shows up in 2028 Medicare premiums.

### How far back does Medicare look for IRMAA?

Generally two years. Social Security uses the most recent tax information the IRS can provide, which is usually the return from two years before the premium year and never more than three, so 2026 premiums are generally based on 2024 returns.

### Can I undo a Roth conversion if it pushes me over an IRMAA line?

No. Since January 1, 2018, a conversion from a traditional IRA, SEP or SIMPLE IRA to a Roth IRA cannot be recharacterized. That is why many people size the conversion near the end of the year, when the rest of their income is clearer.

### Can I appeal IRMAA caused by a Roth conversion?

Social Security lets you ask for a lower IRMAA after a life-changing event that reduced income, such as marriage, divorce, the death of a spouse, loss of income or an employer settlement payment, using Form SSA-44. A conversion you chose to make is not on that list.

### Do I need to make an estimated tax payment on a Roth conversion?

Often. How much tax is withheld from a conversion depends on the withholding election you make with your IRA custodian, and the IRS says you may owe a penalty if you do not pay enough during the year. Publication 505 explains the payment rules, including special rules for higher-income taxpayers.

## Sources

- [IRS, IR-2026-128, IRS reminder: Year-round tax planning can make filing easier (October 23, 2026)](https://www.irs.gov/newsroom/irs-reminder-year-round-tax-planning-can-make-filing-easier)
- [CMS, 2026 Medicare Parts A and B premiums and deductibles, including Part B and Part D income-related monthly adjustment amounts (November 14, 2025)](https://www.cms.gov/newsroom/fact-sheets/2026-medicare-parts-b-premiums-deductibles)
- [SSA, POMS HI 01101.010, Modified Adjusted Gross Income (MAGI)](https://secure.ssa.gov/POMS.nsf/lnx/0601101010)
- [SSA, Request to lower an income-related monthly adjustment amount (Form SSA-44)](https://www.ssa.gov/medicare/lower-irmaa)
- [IRS, IR-2025-103, Tax inflation adjustments for tax year 2026 (Revenue Procedure 2025-32)](https://www.irs.gov/newsroom/irs-releases-tax-inflation-adjustments-for-tax-year-2026-including-amendments-from-the-one-big-beautiful-bill)
- [IRS, Retirement plans FAQs regarding IRAs (conversions and recharacterization)](https://www.irs.gov/retirement-plans/retirement-plans-faqs-regarding-iras)
- [IRS, Estimated taxes](https://www.irs.gov/businesses/small-businesses-self-employed/estimated-taxes)
- [IRS, Net Investment Income Tax](https://www.irs.gov/individuals/net-investment-income-tax)

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Author: James Ustby, CFP®, APMA®, Wealth Advisor, LPL Financial, Durham and Chapel Hill, North Carolina. This material is for general information only and is not intended to provide specific advice or recommendations for any individual. Examples are hypothetical and for illustration only. Securities and advisory services offered through LPL Financial, a registered investment advisor. Member FINRA / SIPC. Certified Financial Planner Board of Standards Center for Financial Planning, Inc. owns and licenses the certification marks CFP® and CERTIFIED FINANCIAL PLANNER® in the United States to Certified Financial Planner Board of Standards, Inc., which authorizes individuals who successfully complete the organization’s initial and ongoing certification requirements to use the certification marks.