Rex says
Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.
Try a scenario
Click to load — tweak from there.Inputs
Result
Total monthly premium
$225.00
Annual cost
$2,700
Part B per person
$185.00
Part D per person
$40.00
IRMAA surcharge per year
$0
Income room before next bracket
$11,000
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One click, a permanent link with your numbers baked in.
How to use this
- 1Enter standard part b premium ($/month).
- 2Enter magi from two years ago ($).
- 3Enter filing status.
- 4Enter full years enrolled late (years).
- 5Enter part d plan premium ($/month).
- 6Enter people on medicare in household (people).
- 7Read your total monthly premium on the right — it updates as you type.
- 8Hit Share to keep the scenario or send it to someone.
About this calculator
Medicare Part B costs most people the standard monthly premium, but three things change that number and each surprises new enrolees. First, income-related monthly adjustment amounts (IRMAA) add a surcharge to both Part B and Part D when modified adjusted gross income from two years earlier exceeds a bracket threshold — and the brackets are cliffs, so a single dollar of extra income can cost hundreds over a year. Second, enrolling late without creditable coverage adds a permanent 10% penalty for every full year you could have enrolled but did not. Third, the hold-harmless provision limits premium increases for many people already receiving Social Security. This calculator applies all three to your figures and shows the annual cost, the surcharge you are paying because of the income lookback, and how far you are from the next bracket — useful when deciding whether to convert a retirement account or realise a gain this year.
Worked example
Using the values the calculator loads with:
Inputs
- Standard Part B premium: 185 $/month
- MAGI from two years ago: 95000 $
- Filing status: Single
- Full years enrolled late: 0 years
- Part D plan premium: 40 $/month
- People on Medicare in household: 1 people
Results
- Total monthly premium: $225.00
- Annual cost: $2,700
- Part B per person: $185.00
- Part D per person: $40.00
- IRMAA surcharge per year: $0
- Income room before next bracket: $11,000
What each field means
Inputs
- Standard Part B premium ($/month)
- The standard part b premium used in the calculation, measured in $/month. Starts at 185 $/month so you have a working example on load. Accepted range: 0–600 $/month.
- MAGI from two years ago ($)
- The magi from two years ago used in the calculation, measured in $. Starts at 95000 $ so you have a working example on load. Accepted range: 0–2000000 $.
- Filing status
- Pick the option that matches your situation — the maths changes per option. Choices: Single, Married filing jointly.
- Full years enrolled late (years)
- The full years enrolled late used in the calculation, measured in years. Starts at 0 years so you have a working example on load. Accepted range: 0–20 years.
- Part D plan premium ($/month)
- The part d plan premium used in the calculation, measured in $/month. Starts at 40 $/month so you have a working example on load. Accepted range: 0–300 $/month.
- People on Medicare in household (people)
- The people on medicare in household used in the calculation, measured in people. Starts at 1 people so you have a working example on load. Accepted range: 1–2 people.
Results
- Total monthly premium
- Returned as a money amount in US dollars and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Annual cost
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Part B per person
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Part D per person
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- IRMAA surcharge per year
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Income room before next bracket
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
Why does income from two years ago matter?
SSA sets IRMAA using the most recent tax return it has, which is normally two years old. That makes the year you retire, sell property, or convert to a Roth the year that sets your premium two years later.
Can I appeal an IRMAA determination?
Yes, using Form SSA-44 after a life-changing event such as retirement, marriage, divorce, or loss of income-producing property. A one-off capital gain is not a qualifying event, which catches many people.
Is the late enrolment penalty permanent?
For Part B, yes — 10% for each full 12-month period you could have enrolled but did not, added for as long as you have Part B. Coverage from active employment generally protects you from it.
Are the bracket amounts fixed?
No, they are indexed and change annually. Update the premium input each year and check the current thresholds; the amounts here are configurable so the tool stays accurate.
Accuracy and limitations
- Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
- Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
- This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Medicare Part B Premium Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/medicare-part-b-premium-calculator
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/medicare-part-b-premium-calculator" target="_blank" rel="noopener">Medicare Part B Premium Calculator — RevenueLab</a> (2026).</p>
Source: [Medicare Part B Premium Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/medicare-part-b-premium-calculator) (2026).