Methodology and source transparency

The four categories of evidence

Every published number on this site falls into one of four buckets:

1. CMS marketplace data. The Centers for Medicare & Medicaid Services publishes the Health Insurance Marketplace Public Use Files (PUF), the Qualified Health Plan Landscape file, and the Open Enrollment Period public-use snapshots. Benchmark plan premiums by rating area, plan tier distributions, and median enrolment figures trace here.
2. KFF (Kaiser Family Foundation) tracking polls and analysis. KFF publishes the year-over-year marketplace premium change tracker, employer-sponsored insurance trend surveys, and the analysis underlying most published year-over-year deltas (such as the 21 to 26 percent 2026 premium increase figure). KFF is treated as authoritative for trend deltas; CMS is treated as authoritative for level figures.
3. HHS Federal Poverty Level (FPL) tables. The annual FPL publication from the Department of Health and Human Services anchors every subsidy-cliff and Medicaid-eligibility calculation on the site. The 100 percent, 138 percent, 250 percent, and 400 percent FPL thresholds used in subsidy maths come from this single source.
4. CMS, IRS, and HHS published limits. The ACA out-of-pocket maximums ($10,600 self-only / $21,200 family for 2026) are set by CMS/HHS in the annual Notice of Benefit and Payment Parameters, not by the IRS. HSA contribution limits come from IRS Rev. Proc. 2025-19, and the ACA affordability percentage (9.96 percent for 2026) from IRS Rev. Proc. 2025-25. These are read directly off the agency PDFs.

Where a figure on a calculator page does not trace to one of these four sources, it is either a multiplier we derived ourselves (in which case the calculation is shown inline) or an industry convention we’ve labelled as such.

Re-verification cadence

• CMS marketplace data: pulled at the start of each open-enrollment period (1 November) and again at the close (15 December, per the shortened federal window from the 2025 Marketplace Integrity and Affordability final rule).
• KFF trend data: spot-checked monthly; any published delta of more than 2 percentage points triggers a refresh.
• HHS FPL tables: pulled annually in January when the new FPL is published.
• IRS Rev. Procs: pulled within 7 days of each new publication.

The footer on every page shows the “Last verified” stamp for the dataset the page depends on, so you can see at a glance whether you’re looking at the latest publication or a snapshot from the previous cycle.

What this site explicitly does not do

• We do not collect personal health information, income figures, or eligibility data. Calculators run entirely client-side; inputs never leave your browser.
• We do not quote you a plan or refer you to a broker. The CMS HealthCare.gov shop tool is the right place to get a binding quote; we link to it from every calculator output.
• We do not reproduce CMS or insurer claims data. Where a premium range is shown, it is a published average from CMS or KFF, not a derived projection.
• We do not name carriers or recommend plans. The goal is to translate the published dollar figures into a decision framework you can use; the binding shop is the marketplace itself.
• We do not invent provenance. Where a figure is a hand-typed estimate from an industry survey rather than a primary publication, the page labels it as such.

Corrections

If you spot a figure that disagrees with the source it cites, please write to [email protected] with the page URL and the contradicting source. Corrections are typically shipped within 48 hours and the page footer is updated with the correction date.