Utah · IRMAA and Social Security

Does Social Security Income Count Toward IRMAA in 2026?

Up to 85% of it does, and the mechanism is not a Medicare rule at all. It is the income-tax formula that decides how much of your benefit is taxable, because whatever lands on line 6b of your 1040 is inside the adjusted gross income Medicare grades. Here is the formula, quoted, the two-year lag, what it costs a Utah couple sitting near the $218,000 line, and the state-tax credit that has usually phased out by the time IRMAA is a question.

Medicare On Main Data Desk

Published September 26, 2026 · 9 min read · Reviewed by Brian Penner, 22+ years in Medicare

The question usually arrives in my Moab office from someone who has just started Social Security: "My benefit is not taxed like wages — does Medicare even see it?" Medicare sees exactly as much of it as the IRS does, and the IRS sees most of it once you have any real retirement income alongside. Nothing about that is a surprise to a tax preparer. It is a surprise to almost everyone else, because the rule that decides it is not in the Medicare statute. It is in section 86 of the tax code, and it was written in 1983 and 1993, long before anyone imagined a Medicare premium that depended on it.

The three steps from a benefit to a premium

Two different rules are stacked here, and it helps to keep them apart. The first is the income-tax rule for how much of a Social Security benefit is taxable. The second is Medicare's rule for what income it grades. Step 1 belongs to the IRS, step 3 to Social Security acting for Medicare, and step 2 is simply the 1040 doing what it always does.

Sources: 26 U.S.C. § 86; IRS Publication 915; 20 CFR § 418.1010; CMS 2026 fact sheet.

Step 1 is the one worth reading in the original. Section 86(a)(1) puts into gross income "social security benefits in an amount equal to the lesser of— (A) one-half of the social security benefits received during the taxable year, or (B) one-half of the excess" of your income over a "base amount," which subsection (c) sets at "$25,000" or "$32,000 in the case of a joint return." Then (a)(2) raises the stakes once income passes an "adjusted base amount" of "$34,000" or "$44,000 in the case of a joint return": the taxable amount becomes 85% of the excess plus a small fixed piece, capped at "85 percent of the social security benefits received during the taxable year." The cap is the sentence that matters. Whatever else you earn, 15% of the benefit stays out of income.

And the income that is tested in (b)(1) is not plain AGI. It is "the modified adjusted gross income of the taxpayer for the taxable year, plus ... one-half of the social security benefits received," where that MAGI is AGI "increased by the amount of interest received or accrued by the taxpayer during the taxable year which is exempt from tax." So municipal bond interest raises the taxable share of your benefit here, and then Medicare adds it again in step 3. The numbers in subsection (c) have never been indexed for inflation since they were written, which is why a couple with a modest pension is already at 85%.

Publication 915 puts the same thing in worksheet form and tells you where it goes: "Report your net benefits (the total amount from box 5 of all your Forms SSA-1099 and RRB-1099) on line 6a and the taxable part on line 6b." Line 6b is the figure that flows into line 11, adjusted gross income. Line 6a does not.

What counts, benefit by benefit

Sources: 26 U.S.C. § 86 (subsections (a), (b) and (d)); IRS Publication 915; 20 CFR § 418.1010.

The 2026 table, and a Utah couple's arithmetic

These are the 2026 tiers from the CMS fact sheet, applied to 2024 modified adjusted gross income. Part B is the total monthly premium including the standard $202.90; Part D is the surcharge added on top of whatever your drug plan charges. Both are per person, so a couple on Medicare pays each column twice.

Source: CMS: 2026 Medicare Parts A & B Premiums and Deductibles (Nov 14, 2025). Married filing separately uses a different schedule.

The example, with the assumptions stated. A Utah couple, filing jointly, both on Medicare. In 2024 their income before Social Security was $170,000: a pension, IRA withdrawals and some dividends, no tax-exempt interest. Their two Social Security benefits totaled $60,000 in box 5. The § 86 test adds half the benefit to the rest: $170,000 plus $30,000 is $200,000, far past the $44,000 adjusted base amount, so the 85% ceiling applies and $51,000 of the benefit goes on line 6b. Their adjusted gross income is $170,000 plus $51,000, or $221,000. With no line 2a to add, that is also their Medicare MAGI, and it is over the $218,000 line. Each of them pays $81.20 more per month for Part B and $14.50 more for Part D in 2026: $95.70 a month, times two people, times twelve months, or $2,296.80 for the year.

Now change one assumption. With the same $170,000 of other income and $50,000 of benefits, the taxable part is $42,500 and the MAGI is $212,500, under the line: no surcharge. The Social Security was the income that crossed, and IRMAA is a cliff, so the extra $10,000 of benefit cost $2,296.80 in premiums on top of the income tax on it. That is the arithmetic behind a planning conversation you should have with a tax professional, not with me: the year you begin benefits raises your MAGI two years later, and the year you take a large IRA withdrawal or convert to a Roth stacks on top of a benefit that is already 85% counted.

The Utah layer: taxed at 4.45%, with a credit that fades

Utah is one of the states that taxes Social Security, and it does so by the simplest possible route: state taxable income begins with federal adjusted gross income, so the $51,000 on line 6b is in it. The state then hands back a credit. Utah Code § 59-10-1042(2) lets "each claimant on a return that receives a social security benefit" claim "a nonrefundable tax credit against taxes otherwise due under this part equal to the product of: (a) the percentage listed in Subsection 59-10-104(2); and (b) the claimant's social security benefit that is included in the claimant's state taxable income for the taxable year." The percentage in § 59-10-104(2) is Utah's flat rate, 4.45% under the current text. In effect, the credit refunds the Utah tax on the benefit.

Then subsection (4) takes it away as income rises: the credit "shall be reduced by $.025 for each dollar by which modified adjusted gross income for purposes of the return exceeds" $54,000 for a single filer, $90,000 for a joint return ($45,000 married filing separately, $90,000 head of household). Utah's MAGI for this purpose, in subsection (1)(d), is AGI plus "any interest income that is not included in adjusted gross income," the same municipal-bond add-back Medicare uses. For the couple in the example, the credit before phase-out would be 4.45% of $51,000, or $2,269.50; a reduction of 2.5 cents per dollar erases it entirely once income passes about $180,780, and they are at $221,000. So the household paying IRMAA in Utah is, almost by definition, also paying full Utah tax on 85% of its Social Security. Subsection (3)(b) adds one more rule: the credit cannot be claimed in the same year as the older retirement credit in § 59-10-1019, so a preparer picks one.

IRMAA comes out of the same check

Most retirees never write a check for Part B; it is deducted from the Social Security deposit, and IRMAA is deducted with it. The 2026 Medicare Trustees Report describes the protection that goes with that arrangement — "a hold-harmless provision in the law that limits the dollar increase in the premium to the dollar increase in an individual's Social Security benefit," covering "roughly 70 percent of Part B enrollees" — and then, in a footnote, the people it leaves out: "About 30 percent of Part B enrollees are not eligible for the hold-harmless provision. This group consists of new enrollees during the year, enrollees who do not receive Social Security benefit checks, enrollees with high incomes who are subject to the income-related premium adjustment, and dual Medicare-Medicaid beneficiaries."

Read that alongside the two-year rule in 20 CFR § 418.1135, which says Social Security uses "your modified adjusted gross income provided by IRS for the tax year 2 years prior." Your 2026 surcharge was set by 2024 income; the benefits you started this year surface in the 2028 premium. If retirement, a spouse's death or a divorce has dropped your income since the return Medicare used, Form SSA-44 lets you ask for a redetermination, and the estimated income you put on it includes the taxable part of your Social Security. Starting benefits is not on the list of life-changing events; stopping work is. Our appeal post walks through the form.

What I would do

First, find lines 6a and 6b on your 2024 and 2025 returns and notice the gap between them. That gap is the 15% Medicare never sees; everything else on 6b is counted. Second, add line 6b's share of line 11 to line 2a and compare the total with $109,000 or $218,000. If you are within one year's benefit of the line, that is the number to take to your tax preparer before the end of the year, because the levers — the timing of IRA withdrawals, a Roth conversion, which account a bond sits in — are theirs, not ours. Third, remember that the Utah credit is a separate question with a much lower threshold; a couple can lose the state credit at $90,000 of income and still be $128,000 short of a federal surcharge.

And keep it in proportion. In Grand County, 33.3% of adults live with high blood pressure and 11.2% with diabetes; of the county's 2,299 Medicare beneficiaries in June 2026, 1,762 were in Original Medicare and 537 in Medicare Advantage. For all of them, the plan chosen between October 15 and December 7 moves next year's costs far more than which tier a Social Security check lands in. IRMAA is a premium; the formulary and the network are the bill.

How we know all this: the Medicare On Main Data Desk frames every article with public data — here, 26 U.S.C. § 86 for the base amounts, the 50% and 85% inclusion rules and the definition of the income tested, quoted as published; IRS Publication 915 for the worksheet thresholds and lines 6a and 6b; 20 CFR § 418.1010 for Medicare's modified adjusted gross income and § 418.1135 for the two-year lookback; the CMS fact sheet of November 14, 2025 for every 2026 Part B and Part D figure; the 2026 Medicare Trustees Report for the hold-harmless provision and footnote 56; Utah Code §§ 59-10-1042 and 59-10-104 for the state credit, its phase-out and the rate; the CMS Medicare Monthly Enrollment file for Grand County (June 2026); and CDC PLACES county data (2023). The worked example is a stated set of assumptions, not a client. No product or carrier is named or recommended. This is education, not tax or investment advice; confirm your own figures with your tax advisor, and plans, costs and eligibility with a licensed agent or Medicare.gov. We take no payment from any carrier to feature a plan.