2026 Medicare IRMAA Calculator for Colorado

How IRMAA brackets are applied to your income

IRMAA works in brackets, not percentages. Social Security takes your modified adjusted gross income from the return two years back, places you in a bracket, and charges the amounts CMS publishes in its 2026 Parts A and B fact sheet.

Social Security mails a notice when IRMAA applies, usually late in the year before it takes effect. If the income figure itself is wrong, for example because you amended that return, ask Social Security to correct it with a copy of the amended return.

1. Find your MAGI: adjusted gross income plus tax-exempt interest, from your 2024 return for 2026 premiums.
2. Choose the table for your filing status. Single and joint returns each have thresholds; married filing separately has a stricter table this tool omits.
3. Compare with the thresholds. In 2026 surcharges start above $109,000 single or $218,000 joint, and the top bracket begins at $500,000 or $750,000.
4. Read two numbers: your total Part B premium and the Part D amount added to your drug plan premium.
5. Apply per person. On a joint return, each spouse enrolled in Medicare pays the bracket amount.

IRMAA mistakes that cost Front Range retirees

• Forgetting one-time income counts. Capital gains, Roth conversions and large IRA withdrawals raise MAGI that year and surface in premiums two years later.
• Overlooking home sale rules. The IRS home sale exclusion lets many owners exclude up to $250,000 of gain, or $500,000 on a joint return. Gain above that counts toward MAGI.
• Not filing form SSA-44 after retiring. If income fell after a life-changing event such as stopping work, reduced hours, marriage, divorce or a spouse’s death, ask Social Security to use newer income on form SSA-44.
• Assuming IRMAA only touches Part B. The Part D add-on applies even when your drug coverage comes through Medicare Advantage.
• Expecting brackets to stay put. CMS publishes new amounts each year; 2027 figures arrive around November 2026.

IRMAA, Colorado income and the other end of the scale

IRMAA is federal. Colorado’s state income tax does not change it, because Social Security works from the federal figures on your return.

Moves that lower MAGI, such as spreading a Roth conversion over several years or timing a property sale, are tax decisions. Run them past a Colorado tax professional first; I am not a tax adviser.

At the other end of the scale, Coloradans with limited income can have the Part B premium paid entirely through a Medicare Savings Program, run with Health First Colorado and applied for at the county Department of Human Services (HCPF). Medicare.gov lists 2026 QI income limits of $1,816 a month for one person and $2,455 for a couple.

If income has fallen sharply since the return Social Security used, both doors can matter: SSA-44 to lower IRMAA now, and a savings program check if income keeps dropping.

Key terms: IRMAA calculator

MAGI for IRMAA

Adjusted gross income plus tax-exempt interest, as reported to the IRS.

Lookback year

The tax year Social Security uses, normally two years before the premium year.

Life-changing event

One of the events listed on form SSA-44, such as work stoppage, that lets a newer year be used.

Part D IRMAA

A separate monthly amount for higher incomes, usually withheld from Social Security checks rather than paid to the plan.

Bracket cliff

The point where one more dollar of MAGI moves you into the whole next premium tier.

Documents for an IRMAA review or SSA-44 request

• Federal returns for the last three years.
• The IRMAA letter from Social Security.
• Proof of the event: a retirement letter, death certificate, divorce decree or employer statement.
• An estimate of this year’s income, plus details of any planned sale, conversion or large withdrawal.