Will a Roth Conversion Increase My Medicare IRMAA Premiums?

A Roth conversion can increase Medicare IRMAA premiums, because the conversion counts as income in the year you convert. IRMAA, the income-related monthly adjustment amount, is an extra charge on Medicare Part B and Part D for people whose income is above thresholds set by Medicare. Those premiums are generally based on income from two years earlier. A conversion in 2026 can affect premiums in 2028, not necessarily the month you convert. The increase is often temporary if your income falls back below the threshold later.

MAGI, or modified adjusted gross income, is the income measure Medicare uses for this test. For IRMAA it starts from adjusted gross income on your tax return and adds some items back, including tax-exempt interest. You do not need to memorize the worksheet to use the idea: if the conversion raises the income Medicare looks at, it can raise the premium. The dollar thresholds and the premium amounts change. Use Medicare.gov's cost pages for the year in question rather than a figure from an old article.

How the two-year lookback works in plain language

Medicare does not see your conversion the week you move the money. It sees the tax return. If you convert in a given tax year, that return is what Social Security, which handles IRMAA determinations, generally uses two years later. A household that converts at 63, before Medicare starts at 65, can still feel the conversion in the first years of Medicare. A household that converts at 68 can see higher premiums at 70, then a drop if later years have less income.

Crossing a threshold by a small amount can move you into the next premium tier for the whole year. Unlike a tax bracket, where only the dollars inside the band are taxed at the higher rate, IRMAA tiers apply to the premium once income crosses the line. That is why people sometimes stop a conversion a little below a published threshold. The threshold for a single filer and a married couple filing jointly are different. Confirm both the tier and your filing status.

An illustration of the tradeoff

Suppose a married couple is considering a conversion that keeps them just under an IRMAA tier, and a larger conversion that crosses it. The larger conversion might reduce future taxable withdrawals, which we discuss in how much to convert each year and converting before RMDs. The smaller conversion might avoid a year or two of higher Part B and Part D premiums. Neither result is automatically cheaper over a lifetime. A one-year premium increase can be a reasonable price for a conversion that lowers taxes for twenty years. It can also be a poor trade if the conversion only moved money you were going to spend soon anyway.

Planning question	What to check
Which tax year will include the conversion?	That year's MAGI, not the year you feel like converting.
Which Medicare year might use that return?	Usually two years later. Life events can support an appeal.
Do we cross a tier by a small amount?	A slightly smaller conversion may stay in the current premium.
Is the premium increase one or two years, or ongoing?	A single high-income year often affects a limited premium window.

Social Security describes appeals when a life-changing event, such as retirement or the death of a spouse, makes the two-year-old return a poor picture of current income. A Roth conversion by itself is not the same thing as retiring. Do not assume an appeal will remove a premium that the conversion itself caused. Read the current SSA and Medicare instructions before you count on relief.

Common mistakes

The most expensive surprise is converting in December without noticing that the income lands on this year's return and the premium lands two years out. Another is using a single filer's threshold for a married couple, or the reverse. People also forget that tax-exempt interest can count in MAGI even though it did not feel like "income" when the bond paid. And some households avoid every conversion to dodge IRMAA, then face larger taxable RMDs later that push them over the same thresholds anyway.

What this means for your retirement plan

Put the conversion, the tax bill, and the possible premium on one page. If a slightly smaller conversion stays under a tier, compare that choice with the larger one over the rest of the retirement, not just this April. How to reduce taxes in retirement includes IRMAA as one of the costs worth planning around, alongside brackets and withdrawal order.

See how retirement income, Roth conversions, and Medicare planning interact for your household.

Frequently asked questions

Does every Roth conversion raise my Medicare premium?

No. If the conversion leaves your IRMAA income measure under the threshold for your filing status, the premium tier may not change. If it crosses a threshold, the premium can rise for the year Medicare ties to that tax return.

How long does an IRMAA increase from a conversion last?

Often for one premium year, because each premium year looks back at a tax return. A conversion every year can keep income high and keep the premium high. A single conversion year usually does not raise premiums for the rest of your life.

What is MAGI for IRMAA?

It is a specific income measure based on your tax return, not simply your paycheck or your IRA withdrawal. Tax-exempt interest is one item people overlook. Medicare and SSA publish the definition used for premiums.

Can I avoid IRMAA by converting after I start Medicare?

Starting Medicare does not shield you. Income after you enroll can still set a later year's premium through the lookback. The timing changes which premium year is affected. It does not remove the test.

Related reading

• How much should I convert to Roth each year?
• Should I do Roth conversions before RMDs begin?
• How can I reduce taxes in retirement?

This article is educational. It is not a prediction of your Medicare premium. IRMAA thresholds and monthly amounts are updated. Use Medicare.gov and SSA.gov for the current figures, and a qualified professional if you need advice on a conversion.