Methodology
Methodology and sources
This page lists every figure the calculators and guides rely on, where it comes from, when we last checked it, and exactly how we calculate the results you see. Last reviewed October 15, 2026.
Where the numbers come from
All premiums and income limits are stored in a single data file per premium year. Each file records its source and either a verified date, meaning we compared every number with the official publication, or a computed date, meaning the numbers are our projection. The calculators and every dollar figure in our guides are produced from these files.
2026 figures (official)
Source: CMS fact sheet, 2026 Medicare Parts B premiums and deductibles. Verified October 4, 2026.
| Constant | Value |
|---|---|
| Standard Part B premium | $202.90 / month |
| Individual limits (2024 MAGI) | $109,000 · $137,000 · $171,000 · $205,000 · $500,000 |
| Joint limits (2024 MAGI) | $218,000 · $274,000 · $342,000 · $410,000 · $750,000 |
| Married filing separately, lived together | $109,000 · $391,000 |
| Part B by tier | $202.90 · $284.10 · $405.80 · $527.50 · $649.20 · $689.90 |
| Part D surcharge by tier | $0 · $14.50 · $37.50 · $60.40 · $83.30 · $91.00 |
The married-filing-separately upper limit is the individual top limit minus the first individual limit ($500,000 − $109,000), which is how the law defines it.
2027 figures (projected)
Computed October 4, 2026, and shown with a "Projected" label everywhere they appear. Method:
- The first limits are projected at $112,000 (individual) and $224,000 (joint) from published inflation data. The law indexes these limits to inflation and rounds them to a multiple of $1,000.
- The middle limits are the 2026 limits multiplied by 112,000 / 109,000 and rounded to the nearest $1,000: $141,000, $176,000 and $211,000 individual; $282,000, $351,000 and $421,000 joint.
- The top limits of $500,000 and $750,000 are fixed by law.
- The married-filing-separately limit is $500,000 − $112,000 = $388,000.
- Premium amounts repeat the 2026 figures until CMS announces the 2027 premiums, expected in November 2026.
When CMS publishes the official 2027 figures, we replace the projection within seven days, change the label, and record the new verification date here.
Rules we apply
- Lookback: the premium for year Y uses MAGI from tax year Y − 2, or Y − 3 if the Y − 2 return is not available. Source: Social Security POMS HI 01101.020, verified October 4, 2026.
- MAGI: adjusted gross income plus tax-exempt interest, plus certain excluded foreign income. Same source.
- Life-changing events: the eight events and the documents listed on Form SSA-44, verified October 4, 2026.
- Boundaries: "more than $109,000" means $109,000 is the standard tier and $109,001 is tier one. The top tier starts at its exact limit. Income is rounded to whole dollars before the tier is found.
How the calculators work
- Tier: the first tier whose upper limit is at or above your rounded MAGI.
- Headroom: the upper limit of your tier minus your MAGI. It is the amount you can add without changing tier. There is no headroom in the top tier.
- Yearly cost: (Part B premium + Part D surcharge) × 12, per person, rounded to cents. A joint return counts two people on Medicare unless you choose otherwise.
- Cost of crossing: the yearly cost of the next tier minus the yearly cost of your tier.
- Roth headroom: the headroom left after adding your other planned income (capital gains, required distributions and other income) to your base MAGI.
- SSA-44 checklist: a qualifying event plus a drop in income suggests Form SSA-44 may apply; events not on the form never qualify. Social Security makes the actual decision.
The calculation code is tested automatically against more than twenty cases, including every boundary dollar of the 2026 tables, before each update is published.
Examples in our guides
Worked examples use invented people and round numbers. Every dollar result in an example is produced by the same calculation code as the tools, not typed by hand, and the date in each guide's byline shows when it was last updated. Other figures, such as the Uniform Lifetime Table factors for required distributions or the home-sale exclusion, are cited to the relevant IRS publication in the guide.
Corrections policy
If you believe a figure or a rule is wrong, email contact@irmaacliff.com with the page and the issue. We check every report against the official source. Confirmed errors are fixed promptly, and material corrections are noted on the affected page with the date.
Independence
IRMAA Cliff is not affiliated with or endorsed by Medicare, CMS, the Social Security Administration or any government agency. Advertising and affiliate relationships never change our numbers. See about us and our affiliate disclosure.