Methodology
Methodology
A calculator is only as good as the rule behind it. This page explains where the figures come from, how the formulas are checked, and what the tools do not cover.
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Where the figures come from
The data layer uses official publications from the Centers for Medicare & Medicaid Services, Medicare.gov, the Social Security Administration, the Department of Health and Human Services, the Internal Revenue Service, and state Medicaid agencies. Each figure keeps its year, source link, and checked date with the value.
A figure that has not been checked against an official source is flagged for review rather than presented as settled. The visible source table on each calculator shows the figure, the year, the agency, the link, and the checked date.
How the formulas are tested
Every formula has automated tests for the normal case, boundary values, zero values, and the cliff or threshold that matters to that formula. A threshold is checked one unit below, at, and one unit above the line. A penalty is checked for a partial year and a full period. A state program is checked at its income and resource limits.
Each formula also has hand-worked examples recorded in the project's verification log. The examples use published tables or official worked examples where one exists. Where no official worked example exists, the entry says so and shows the hand calculation from the published rule.
What the calculators do not cover
- Plan-specific premiums, networks, formularies, and out-of-pocket costs are not included unless the page says so.
- A Marketplace benchmark premium is not invented. The ACA comparison separates known Medicare premiums from the unknown plan price.
- State-specific Medicare Savings Program disregards and case rules are not fully modeled. The tool applies the federal tests for covered states and tells the reader to apply through the state agency.
- Tax filing changes, future income, and events after the checked date can change a result.
- Medigap, Medicare Advantage, and Part D plan choices are outside the current calculator scope.
How often figures change
The annual update checklist covers the fall Medicare premium and IRMAA release, the IRS affordability percentage, the federal poverty guidelines, and state savings-program limits. A figure is updated when the official source publishes the new value, not before.
The current data year is shown on every calculator. A future year is not added until the official table is available.
Why a result can differ from an agency decision
An agency applies your full record, current state rules, and its own verification. A calculator applies the inputs you provide and the simplified rule described on the page. Treat the result as a way to understand the rule and prepare for the official process, not as a final determination.
Corrections
If a formula, source, or boundary test is wrong, send the page and the official source to ihsanaslamm@gmail.com. The corrections page explains what to include and how changes are recorded.
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