How to Calculate MAGI for IRMAA
October 4, 2026
For most retirees, IRMAA MAGI is two numbers from the federal tax return added together. Those are adjusted gross income (Form 1040, line 11, or line 11a on a 2025 return) and tax-exempt interest (line 2a). Social Security compares the total with the thresholds for IRMAA, the income-related monthly adjustment amount added to Medicare Part B and Part D premiums. For 2026 premiums, SSA generally uses your 2024 return, and IRMAA starts above $109,000 of MAGI for single filers or $218,000 on a joint return (SSA POMS HI 01101.010).
IRMAA MAGI (most retirees) = AGI (line 11 or 11a) + tax-exempt interest (line 2a)
A smaller group needs extra add-backs, mainly people who excluded foreign earned income or income from Puerto Rico or another U.S. territory. The calculation steps below cover those.
You won't find "MAGI" printed anywhere on your 1040. Taxable income (line 15), the number most of us watch, isn't used at all. And the municipal bond interest you never paid federal tax on gets added right back in.
Precision matters because IRMAA works in tiers, not a smooth slope. Crossing a threshold by even one dollar moves you into the next premium tier, and on a joint return the higher premium applies to each spouse who's enrolled. It generally stays in place for that premium year unless SSA makes a new determination, for example after an amended or corrected return or a qualifying life-changing event.
Below: where each piece sits on the form, which return counts for which premium year, a worked example of a couple who missed by $1,400, and when SSA may use newer or corrected income instead.
How to calculate your IRMAA MAGI from Form 1040
For most people, everything you need is on page 1 of Form 1040. The hard part is making sure it's the right year's return.
- Pull the right return. For 2026 Medicare premiums, that's your 2024 Form 1040. The next section maps other years.
- Find adjusted gross income. On a 2024 return it's line 11. On the 2025 form the IRS renumbered it: AGI is line 11a, repeated as line 11b at the top of page 2. Same number either way (IRS Form 1040, 2025).
- Find tax-exempt interest on line 2a. This is mostly municipal bond interest, including exempt-interest dividends from muni bond funds. Your brokerage's year-end 1099 lists it separately from taxable interest.
- Add the two. The total is your IRMAA MAGI, unless one of the rarer add-backs below applies. If you file jointly, it's the combined figure from the joint return, and SSA applies that same number to each spouse who's enrolled (Social Security Act §1839(i)(4)).
- Compare it with the bracket table for your filing status and premium year, further down this page.
SSA's operating manual describes MAGI using just those two lines, and that covers most retirees. The statute behind it also adds back three exclusions: foreign earned income you excluded, income excluded because it was earned in Puerto Rico or another U.S. territory, and excluded savings-bond interest used for education (Social Security Act §1839(i)(4)(A)). If any of those appear on your return, your IRMAA MAGI is higher than lines 11 and 2a alone suggest.
Which year's tax return Social Security uses
Social Security generally uses your tax return from two years before the premium year, so your 2024 return sets 2026 premiums. If the IRS can't supply that year yet, SSA uses the return from three years before and never goes further back (SSA POMS HI 01101.010).
| Medicare premium year | Tax return SSA normally uses | AGI line on that return | Brackets |
|---|---|---|---|
| 2026 | 2024 | Line 11 | Published: $109,000 single, $218,000 joint |
| 2027 | 2025 | Line 11a | Not yet announced; CMS released the 2026 figures on November 14, 2025 |
| 2028 | 2026 | 2026 form | The income you're earning this year |
The lag explains two things that catch people off guard. A Roth conversion you do in 2026 won't touch your premiums until 2028. And someone who retired in 2025 can get a 2026 IRMAA notice based on 2024, a year of full salary. Stopping work is a qualifying life-changing event, so that person can ask SSA to use more recent income instead (SSA POMS HI 01120.001).
When SSA has to use the older return, the law requires a correction once the right year's data arrives (Social Security Act §1839(i)(4)(B)). You don't have to wait for that: you can give SSA a signed copy or transcript of the two-year-old return yourself (SSA POMS HI 01120.001).
Already paying IRMAA based on income you no longer receive? Jump to When SSA may use newer or corrected income.
What counts toward IRMAA MAGI, and what doesn't
Roth conversions and municipal bond interest both count toward IRMAA MAGI. Qualified Roth IRA withdrawals and qualified charitable distributions don't. The general rule: if an item lands in AGI or on line 2a, it counts; if it's excluded from income or subtracted after AGI, it doesn't.
| Item | Counts toward IRMAA MAGI? | Where it shows on Form 1040 |
|---|---|---|
| Wages, salary | Yes | Line 1z |
| Taxable interest (CDs, savings, Treasuries) | Yes | Line 2b |
| Tax-exempt interest (municipal bonds, muni funds) | Yes, added back | Line 2a |
| Dividends | Yes | Line 3b only; qualified dividends on 3a are already inside it |
| Traditional IRA withdrawals and RMDs | Yes, the taxable amount | Line 4b |
| Roth conversions | Yes, the taxable amount | Line 4b |
| Pensions and annuities | Yes, the taxable amount | Line 5b |
| Social Security | Only the taxable portion | Line 6b, not 6a |
| Capital gains, net of losses | Yes | Line 7 (7a on the 2025 form) |
| Rental, business, other income | Yes | Line 8, via Schedule 1 |
| HSA contributions, deductible IRA contributions, other adjustments | Lower it | Line 10, via Schedule 1 |
| Qualified charitable distributions (QCDs) | No | Included in 4a, excluded from 4b |
| Qualified Roth IRA withdrawals | No | Not included in AGI |
| Home-sale gain covered by the exclusion | No | Excluded gain doesn't reach line 7 |
| Standard, itemized and senior deductions | No | Lines 12 and 13 (12e to 13b on the 2025 form), below AGI |
A few of these rows trip people up.
Selling investments counts only the gain. Sell $100,000 of fund shares you bought for $70,000 and $30,000 goes into AGI, not $100,000. In a taxable account, watch for mutual fund capital-gain distributions, which can arrive late in the year whether you sold anything or not.
A QCD lets you give from an IRA without adding to MAGI. If you're 70½ or older and the IRA custodian sends the money straight to a qualified charity, it's excluded from gross income, up to an annual limit (IRS). Taking the cash yourself and then donating it doesn't work the same way.
Deductions below AGI don't help. The new deduction of up to $6,000 for people 65 and older, available for tax years 2025 through 2028, flows through Schedule 1-A to line 13b (IRS Publication 6142). That's below line 11a. It can lower your income tax, but your IRMAA MAGI doesn't move. The same is true of charitable deductions and medical expenses you itemize.
On the home sale: the exclusion covers up to $250,000 of gain, or $500,000 on a joint return, if you meet the ownership and use tests (IRS Topic 701). Gain above that is taxable and does count.
Worked example: a couple $8,000 under on AGI, $1,400 over on MAGI
The couple below is hypothetical, and the numbers illustrate the arithmetic rather than recommend a conversion amount. A married couple files a joint 2024 return. In 2026 he's 67 and enrolled in Part B and a Part D plan. She's 64 and won't be on Medicare until next year. In 2024 they converted $85,000 from a traditional IRA to a Roth.
| Form 1040 line (2024) | What it is | Amount |
|---|---|---|
| 2b | Taxable interest | $5,200 |
| 3b | Ordinary dividends | $12,400 |
| 4b | Roth conversion | $85,000 |
| 5b | Pension, taxable amount | $48,000 |
| 6b | Social Security, taxable portion | $40,800 |
| 7 | Capital gains | $18,600 |
| 10 | Adjustments to income | $0 |
| 11 | Adjusted gross income | $210,000 |
| 2a | Tax-exempt interest (muni fund) | $9,400 |
| IRMAA MAGI | $219,400 |
If they'd checked only AGI, they'd have seen $8,000 of room under the $218,000 joint threshold. The muni interest erased it and then some.
At $219,400, he lands in the first IRMAA tier for 2026. His Part B premium is $284.10 a month instead of $202.90, and he pays an extra $14.50 a month on top of his Part D plan premium (SSA POMS HI 01101.020). That's $81.20 a month of Part B IRMAA plus $14.50 of Part D IRMAA, or $1,148.40 for the year.
She pays nothing extra, because she isn't enrolled. Had they both been on Medicare, each would owe the same surcharge: $2,296.80 for the household.
Look at how thin the margin was. A conversion $1,400 smaller would have put MAGI at exactly $218,000, and the first tier only starts at more than $218,000. In real life you'd want a wider cushion than that, because dividends and fund distributions often aren't final until December.
Crossing a threshold doesn't, by itself, give anyone grounds to ask SSA for a different number. A voluntary Roth conversion isn't on SSA's list of life-changing events, so this couple's 2026 surcharge generally stands. The effect is usually temporary, though: each premium year is set from its own tax year, so their 2027 premiums will be based on their 2025 return.
2026 IRMAA brackets: where your MAGI lands
These are the official 2026 amounts, based on 2024 MAGI, per person, per month. The standard Part B premium is $202.90 (CMS). In the higher rows, the Part B figure is that standard premium plus the Part B IRMAA. The Part D column shows only the IRMAA, which is added to whatever your plan charges (SSA POMS HI 01101.020).
| 2024 MAGI: single, head of household, qualifying surviving spouse | 2024 MAGI: married filing jointly | Part B premium | Part D IRMAA (added to your plan premium) |
|---|---|---|---|
| $109,000 or less | $218,000 or less | $202.90 | $0 |
| Over $109,000 to $137,000 | Over $218,000 to $274,000 | $284.10 | $14.50 |
| Over $137,000 to $171,000 | Over $274,000 to $342,000 | $405.80 | $37.50 |
| Over $171,000 to $205,000 | Over $342,000 to $410,000 | $527.50 | $60.40 |
| Over $205,000, under $500,000 | Over $410,000, under $750,000 | $649.20 | $83.30 |
| $500,000 or more | $750,000 or more | $689.90 | $91.00 |
Read the rows as cliffs. MAGI one dollar above a threshold puts you in the higher row for that premium year. Your actual premium can also differ for reasons unrelated to income, such as a late-enrollment penalty.
Married filing separately works differently if you lived with your spouse at any point during the tax year. Above $109,000 you go straight to $649.20 for Part B and $83.30 for Part D, and at $391,000 or more it's $689.90 and $91.00.
Thresholds are adjusted for inflation each year. SSA's table shows the single-filer line rising from $97,000 for 2023 to $109,000 for 2026. If you're estimating 2027 or 2028 premiums, the 2026 lines are a reasonable placeholder, but treat any result as an estimate until CMS publishes the brackets for that premium year.
AGI vs. IRMAA MAGI vs. taxable income
AGI and IRMAA MAGI differ by your tax-exempt interest, plus the rare add-backs described above. Taxable income is a third, smaller number, and IRMAA doesn't use it.
| Measure | Form 1040 line | How it's built | Role in IRMAA |
|---|---|---|---|
| Adjusted gross income | 11 (11a on the 2025 form) | Total income minus Schedule 1 adjustments | The starting point |
| IRMAA MAGI | Not printed on the form | AGI plus tax-exempt interest, plus rare add-backs | The number compared with the thresholds |
| Taxable income | 15 | AGI minus standard or itemized deductions and other deductions | None |
Other federal rules use their own versions of "MAGI," with different add-backs. If tax software or a worksheet shows a figure labeled MAGI, check which rule it was built for before you compare it with IRMAA brackets.
Edge cases that change the calculation
One spouse on Medicare, the other not yet
On a joint return, both spouses share one MAGI, but only a spouse enrolled in Medicare pays a premium. So the same income can cost one surcharge in one year and two in a later year, once the younger spouse enrolls. Before a conversion or large sale, check which premium year it lands in and how many of you will be on Medicare by then.
If the younger spouse has Marketplace (ACA) coverage, the same income counts there too, under different rules. Marketplace MAGI also adds non-taxable Social Security (HealthCare.gov), and subsidies are based on the same year's income (Georgetown Navigator Guide). A 2026 Roth conversion could therefore affect the couple's 2026 Marketplace subsidy and the Medicare spouse's 2028 IRMAA.
Married filing separately
If you file separately and lived with your spouse at any time during the tax year, the harsher table above applies. If you lived apart the entire year, it doesn't (Social Security Act §1839(i)(3)(C)(iii)). The IRS data shows only your filing status, so you'd need to tell SSA and provide your return or a signed statement (SSA POMS HI 01120.001).
The year of a marriage, divorce or death
Joint income from two years ago may no longer describe your household. A surviving spouse's premiums, for example, may be set from a joint return that still included the late spouse's pension. Death of a spouse, marriage and divorce are all events SSA can revisit (see the next section).
An amended return
If you amended the tax return SSA used, it can make a new determination from the amended figures without a formal appeal. SSA asks for the amended return plus the IRS letter acknowledging it, or an IRS transcript (SSA POMS HI 01120.001).
When SSA may use newer or corrected income
If SSA's income figure looks wrong, recompute IRMAA MAGI from the return for the tax year SSA used. If the numbers don't match, or your income has fallen since that year, you may be able to request a new initial determination. That's a fresh decision based on better information, and it doesn't require a formal appeal (SSA POMS HI 01120.001).
| Your situation | What SSA generally needs |
|---|---|
| You amended the return SSA used | The amended return, plus the IRS letter acknowledging it or a transcript |
| The IRS data itself was wrong | Correction from the IRS first (1-800-829-1040), then proof of it |
| SSA used three-year-old data, and you have the two-year-old return | A signed copy or transcript of that return |
| You filed separately and lived apart from your spouse all year | Your Form 1040, or a signed statement plus your spouse's last known address |
| A qualifying life-changing event lowered your income | Proof of the event, plus the more recent year's MAGI or a signed estimate |
SSA's list of qualifying life-changing events is short: death of a spouse, marriage, divorce or annulment, work reduction, work stoppage, loss of income-producing property, loss of employer pension income, and an employer settlement payment. The event has to cause a significant drop in MAGI, or a filing-status change that puts you in a lower threshold table (SSA POMS HI 01120.001). Form SSA-44 is the usual way to ask, but it's optional; you can also make the request by phone or at an appointment (SSA).
One detail married couples miss: a new determination applies only to the person who asks for it. If you're both paying IRMAA, each spouse has to make their own request.
The limits are real. A Roth conversion, a capital gain you chose to take or a large IRA withdrawal isn't on that list. The list is about events like those above, not one-time income you chose to realize. If one of those pushed you over, a life-changing-event request generally won't remove the surcharge. The cost is usually confined to the one premium year tied to that tax year.
If you believe SSA made a different kind of error, you can request a reconsideration, which is the formal appeal. Confirm the deadline with SSA early, so it doesn't pass while you gather paperwork.
Retired, cut back on work, divorced, married or lost a spouse since the tax year SSA used?
If that change significantly lowered your income, you may be able to ask Social Security to base your IRMAA on newer income instead. Losing pension income can count too. SSA calls these life-changing events.
Not sure whether yours fits? CheckIRMAA's free check shows whether your situation appears to match SSA's rules.
- 3 short questions, about 2 minutes
- Free to see your result
- No name, email or Social Security number
Free eligibility check. CheckIRMAA is independent of SSA, and SSA makes the final determination.
What to gather before you run your own numbers
For a premium year that's already set, you need the return from two years before it. For one you can still influence, you need a forecast of this year.
- Your Form 1040 for the tax year in question: 2024 for 2026 premiums, 2025 for 2027.
- Your IRMAA notice from SSA, if you received one, so you can match its tax year to your own math.
- Year-end tax forms: Form 1099-R for IRA withdrawals and conversions, Form SSA-1099 for Social Security, and your brokerage's consolidated 1099 for interest, dividends, tax-exempt interest and sales.
- This year's moving parts: year-to-date income, any RMD still due, planned conversions or asset sales, and an allowance for December fund distributions.
- Each spouse's Medicare start date, because that decides how many surcharges a given year's income could trigger.
The brackets tell you where the lines are. The harder question is where your own income sits against them. And if you're already paying IRMAA based on a year that no longer reflects your income, the next question is whether SSA will let you use a newer number.
Find out whether SSA may let you use newer income
SSA may be calculating your IRMAA from a tax year that no longer reflects what you earn today. CheckIRMAA's free check asks three short questions to see whether your situation appears to match SSA's rules for a new determination.
- About 2 minutes
- Free result
- No name, email or Social Security number
If your situation appears to qualify and you want help, CheckIRMAA can prepare a filled SSA-44 packet for a one-time $149. It includes a professional review of the completed form, an evidence checklist for your situation and a filing guide; you submit it to SSA yourself. The paperwork listed above matters at that stage.
CheckIRMAA is independent of SSA, CMS and Medicare. SSA makes the final decision, and no result guarantees a lower premium.
This article is general information about federal rules as of the date above, not tax, legal or financial advice.
Sources
- SSA POMS HI 01101.010, Modified Adjusted Gross Income (MAGI): MAGI definition, lookback rule, 2023 to 2026 thresholds
- SSA POMS HI 01101.020, IRMAA Sliding Scale Tables: 2026 Part B and Part D amounts, married-filing-separately table
- Social Security Act §1839: statutory MAGI definition, add-backs, joint-return and separate-filer rules
- CMS, 2026 Medicare Parts A & B Premiums and Deductibles: $202.90 standard Part B premium, November 14, 2025 release
- IRS Form 1040 (2025): line 2a, line 11a and line 13b placement
- IRS Publication 6142, Additional Deduction for Seniors
- IRS, Qualified charitable distributions
- IRS Topic 701, Sale of your home
- HealthCare.gov, Modified adjusted gross income
- Georgetown Navigator Resource Guide, income counted for premium tax credits
- SSA POMS HI 01120.001, New Initial Determinations: qualifying events, amended returns, evidence
- SSA, Request to lower an IRMAA and Form SSA-44