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California CAPS Formula Research
Answer: Yes, the CAPS formula is fully published, standardized, and calculable.
Source: 2026 California Premium Subsidy Program Design — Covered California Board, July 28, 2025
How CAPS Works
The California Additional Premium Subsidy (CAPS) uses the exact same formula as federal APTC, but with California's own (lower) applicable percentage table. The state subsidy is the difference between the two calculations.
Federal APTC = SLCSP - (IRS_applicable_% × income / 12)
CA Total = SLCSP - (CA_applicable_% × income / 12)
CAPS = CA Total - Federal APTCSince CA's percentages are lower than the IRS percentages, the consumer's expected contribution is lower, and the difference becomes the state subsidy.
Same inputs: SLCSP premium, income, household size, FPL Only difference: which applicable percentage table is used
The Two Tables
2026 California Applicable Percentage Table
| Household Income (% FPL) | Initial % | Final % |
|---|---|---|
| 100% up to 150% | 0.00% | 0.00% |
| Above 150% up to 165% | 3.19% | 3.91% |
| Above 165% | No state subsidy |
2026 Federal Applicable Percentage Table (IRS Rev. Proc. 2025-25)
| Household Income (% FPL) | Initial % | Final % |
|---|---|---|
| Below 133% | 2.10% | 2.10% |
| 133% up to 150% | 3.14% | 4.19% |
| 150% up to 200% | 4.19% | 6.60% |
| 200% up to 250% | 6.60% | 8.44% |
| 250% up to 300% | 8.44% | 9.96% |
| 300% up to 400% | 9.96% | 9.96% |
| Above 400% | No federal subsidy |
What This Means for Different Scenarios
100-150% FPL (like our test case at 138.6%)
- CA says: contribute 0% of income
- Federal says: contribute 2.10-4.19% of income
- CAPS = the entire federal contribution amount (since CA contribution = $0)
- This means CA effectively gives these people $0 contribution — the state pays the difference
150-165% FPL
- CA says: contribute 3.19-3.91%
- Federal says: contribute 4.19-6.60%
- CAPS = the difference in contribution percentages × income / 12
- Smaller subsidy, but still real savings
Above 165% FPL
- No state subsidy. Federal APTC only.
- Our federal-only calculation is exact for these households.
Verification Against API Data
| Component | Our Calculation | Covered CA API | Gap | Explanation |
|---|---|---|---|---|
| Federal APTC | $839.06 | $833.95 | $5.11 | Age-curve rounding (we derive from age-40 rate) |
| CAPS | $87.20 | $92.75 | $5.55 | Same rounding (CAPS = federal contribution when CA% = 0) |
| CAPC | $2.00 | $2.00 | $0.00 | Exact ($1/member × 2) |
| Total | $928.26 | $928.70 | $0.44 | Near-exact |
The $5.55 gap in CAPS is the same $5.11 SLCSP rounding propagating through. With exact per-age rates (not derived from age-40), this closes to near-zero.
The CAPC ($1/Member Credit)
The capc: 2 field in the API ($2.00 for 2 members) appears to be the statutory California Premium Credit referenced on page 3 of the rates PDF: "All Covered California members receive a monthly $1, California Premium Credit, which is funded by the state's general budget."
- Fixed: $1 per covered member per month
- Universal: applies to ALL Covered California enrollees, not just subsidy-eligible
- Simple: just member_count × $1
Can We Calculate This for Any CA Household?
Yes. The variables needed are:
- Income — same as federal
- Household size — same as federal (for FPL calculation)
- SLCSP premium — from rate data (same benchmark used for both federal and state)
- Number of covered members — for the $1/member CAPC
- California's 2-row percentage table — published annually by Covered California Board
The formula is deterministic. No black-box variables. No county-specific adjustments. No age-specific adjustments beyond what's already in the SLCSP calculation.
Implication for Other States
Each state with its own subsidy program would need similar research:
- Find their published applicable percentage table
- The formula structure is likely similar (difference between state and federal contribution)
- The number of states is small (~5 states have their own premium subsidies)
States to research:
- New York (Essential Plan / Basic Health Program — different structure)
- Colorado (Colorado Option)
- Washington (Cascade Care)
- Others — most SBE states do NOT add state subsidies
For the ~16 SBE states without state subsidies, our federal APTC calculation is the complete answer.
Reconciliation Caps (for reference)
If consumer's actual income differs from projected, repayment is capped:
| Household Income (% FPL) | Single Filer | Other Filers |
|---|---|---|
| Less than 200% | $300 | $600 |
| 200-300% | $775 | $1,550 |
| 300-400% | $1,300 | $2,600 |
| 400-500% | $2,000 | $4,000 |
| 500-600% | $3,000 | $6,000 |
| 600-700% | $4,200 | $8,400 |
Research completed April 7, 2026.Source: 2026 CA Premium Subsidy Program Design
