References

Data sources

New to the affordability test? Read how the ICHRA affordability threshold is calculated: the formula, the three safe harbors, class rules and a worked example.

• CMS Marketplace API (marketplace.api.healthcare.gov (opens in a new tab)): states, counties, ZIP code to county, issuers, and household second-lowest-cost silver plan (SLCSP) and lowest-cost silver plan (LCSP) lookups for plan year 2026.
• CMS 2026 plan rate public use files (Rate PUF): each plan's filed premiums by rating area and age, used to scale premiums from age 30 to every other age. CMS Marketplace public use files (opens in a new tab)
• HUD USPS ZIP code to county crosswalk: which county (or counties) each ZIP code falls in. HUD USPS ZIP crosswalk files (opens in a new tab)
• HHS poverty guidelines: the federal poverty line used by the FPL affordability safe harbor. HHS poverty guidelines (opens in a new tab)
• Age rating curves: the federal default age curve (45 CFR 147.102 (opens in a new tab)), plus the state-specific curves of Alabama, Mississippi, and Oregon (a flat 0.635 for ages 0-20, the federal default from 21 on) and Utah. CMS market rating reforms (state age curves) (opens in a new tab)
• MNsure (enroll.mnsure.org (opens in a new tab)): Minnesota runs its own exchange, so Minnesota plan data comes from MNsure rather than CMS.
• IRS ICHRA affordability percentage: 9.96% for 2026, applied to the self-only LCSP premium. IRS Rev. Proc. 2025-25 (PDF) (opens in a new tab)

For a fuller description of each source and how it's used, see our data sources.