🏥 SubsidyCalc

Methodology & Data Sources

SubsidyCalc uses official federal and state data to power its calculators and eligibility guides. This page documents our data sources, calculation methods, update schedule, and known limitations.

Data Sources

• HHS ASPE — Federal Poverty Level (FPL) guidelines, published annually (typically in January). These thresholds determine eligibility brackets for both marketplace subsidies and Medicaid.
• CMS (Centers for Medicare & Medicaid Services) — Medicaid and CHIP enrollment data, state-level eligibility thresholds, waiver approvals, and expansion status.
• HealthCare.gov — Marketplace benchmark Silver plan (SLCSP) premium data, plan availability, and enrollment rules.
• KFF (Kaiser Family Foundation) — ACA subsidy formula documentation, applicable percentage tables, and policy analysis used to validate our calculations.

How the Subsidy Calculator Works

The ACA subsidy calculator uses the actual formula defined in the Affordable Care Act:

1. Determine FPL percentage — Your household income is compared against the Federal Poverty Level for your household size.
2. Look up applicable percentage — Based on your FPL bracket, the ACA defines a maximum percentage of income you're expected to contribute toward your benchmark plan premium.
3. Calculate expected contribution — Your income multiplied by the applicable percentage.
4. Calculate subsidy — The benchmark Silver plan (SLCSP) premium minus your expected contribution. If the result is positive, that's your estimated monthly premium tax credit.

Premiums are age-adjusted using the federal 3:1 age curve rating factors. State-average benchmark premiums are used as estimates; actual premiums vary by county and rating area.

Medicaid Eligibility Data

Each state Medicaid page compiles eligibility information from official state Medicaid agency sources. Income limits are expressed as percentages of the Federal Poverty Level for key coverage groups (adults, children, pregnant women, aged/disabled). We track each state's Medicaid expansion status, enrollment figures from CMS reporting, and any active Section 1115 waivers that modify standard eligibility rules.

Special cases are documented per state. For example, Wisconsin covers adults up to 100% FPL through a waiver (despite not formally expanding Medicaid), and Alaska and Hawaii use adjusted FPL thresholds that differ from the 48 contiguous states.

Update Schedule

• FPL guidelines — Updated annually when HHS publishes new poverty guidelines (usually January)
• Marketplace/subsidy data — Updated annually ahead of Open Enrollment with new benchmark premiums and applicable percentage tables
• Medicaid state pages — Updated when states change eligibility thresholds, approve new waivers, or modify expansion status

Known Limitations

• Subsidy estimates use state-average benchmark premiums. Your actual subsidy depends on the Second Lowest Cost Silver Plan in your specific county or rating area.
• Medicaid rules change at the state level through waivers, legislative action, and administrative decisions. There may be a delay between a state policy change and our update.
• The calculator provides estimates for planning purposes. For exact subsidy amounts and plan enrollment, use HealthCare.gov or your state's marketplace during Open Enrollment.
• Cost-Sharing Reduction (CSR) estimates are based on standard ACA actuarial value tiers and may not reflect plan-specific benefit designs.

Corrections

If you find an error in our data or calculations, please contact us with the page URL, the specific data point in question, and a source link. We take data accuracy seriously and will verify and correct issues promptly.