Breach filing
ArchivedKaiser Foundation Health Plan, Inc.: 13,400,000 individuals, Apr 2024.
Kaiser Foundation Health Plan, Inc. reported a breach of unsecured protected health information to the HHS Office for Civil Rights on 12 April 2024. The filing records the organisation as a health plan in California and lists 13,400,000 individuals affected, which makes it the 1st largest of the 776 California filings on the register and the 2nd largest of the 741 filings submitted nationally in 2024. Among the 66 California filings made in 2024 it ranks 1st.
Individuals affected
13,400,000
As reported to HHS
Modelled cost (IBM 2025)
$2.14B
Upper bound, method shown
Rank in CA
1st
of 776 California filings
Rank in 2024
2nd
of 741 filings nationally
Section F.1 / The filing
As posted by HHS OCR
Every value below is the portal's own field for this filing, plus its rank within the register.
- Covered entity type
- Health Plan
- Individuals affected
- 13,400,000
- Breach submission date
- 12 April 2024
- Submission year
- 2024
- Type of breach
- Unauthorized Access/Disclosure
- Location of breached information
- Network Server
- Business associate present
- No
- State
- California (CA)
- Portal status
- listed in the HHS OCR breach portal archive
- Rank in California by size
- 1st of 776
- Rank in 2024 nationally
- 2nd of 741
- California median filing
- 3,553 individuals
- Register id (derived)
- CA-20240412-kaiser-foundation-health-plan
Section F.2 / In context
Where this filing sits in California and in 2024
OCR classifies the incident as unauthorized access or disclosure, with the breached information held in a network server. Unauthorized Access/Disclosure is the type recorded on 174 of the 776 California filings (22%) and on 15% of all filings submitted in 2024. Network Server appears on 43% of California filings.
No business associate is recorded on the filing; 33% of California filings do involve one. At 13,400,000 individuals the breach is 3,771 times the California median filing of 3,553 and 3,350 times the national median of 4,000 across all 7,884 filings. It is one of 149 filings on the register of one million or more individuals.
As of 28 August 2026 the case is listed in the HHS OCR breach portal archive. OCR's closing summary of the case is reproduced in full below.
California's breach notification statute (Cal. Civ. Code 1798.82) requires notice to affected residents within 30 calendar days of discovery (effective 1 January 2026, SB 446). Its attorney general threshold: more than 500 California residents. The HIPAA Breach Notification Rule ran alongside it: notice to affected individuals and to HHS without unreasonable delay and no later than 60 days after discovery, which is the clock that put this filing on the portal.
Multiplying 13,400,000 individuals by IBM's $160 customer-PII cost per record (Cost of a Data Breach 2025, the figure the site's calculator uses) gives a modelled $2.14B; the 2026 edition's $192 gives $2.57B. Both are modelled estimates with the method shown, not costs disclosed by Kaiser Foundation Health Plan, Inc.. Because the filing is above the roughly 100,000-record range in which the per-record figure is reliable, the result is an upper bound, not an estimate: fixed costs are spread across far more records at this scale.
Section F.3 / OCR closing summary
The portal's archived description, in full
Written by the Office for Civil Rights when the case was closed and reproduced verbatim from the HHS export.
The covered entity (CE), Kaiser Foundation Health Plan, Inc., reported that it disclosed the protected health information (PHI) for up to 13,134,908 individuals while using third-party tracking technologies. The PHI involved clinical, demographic, and financial information. The CE notified HHS, affected individuals, and the media. In response to the breach, the CE: removed all third-party tracking technologies from its authenticated online platforms, trained or retrained workforce members, and implemented additional administrative safeguards.
Section F.5 / Modelled cost
13,400,000 individuals through IBM's per-record figures
Modelled cost / method shown, not a disclosed cost
Upper boundIBM 2025 customer PII, $160 per record
$2.14B
13,400,000 x $160
IBM 2026 customer PII, $192 per record
$2.57B
13,400,000 x $192
Method: individuals affected, as reported by Kaiser Foundation Health Plan, Inc. to HHS, multiplied by IBM's customer-PII cost per record (Cost of a Data Breach 2025 Figure 6 and the 2026 edition). No cost has been disclosed by the entity for this filing; the figure is a planning estimate, not a fact about the breach. IBM's per-record figures come from mid-volume breaches and IBM cautions against applying them to breaches involving millions of records; the site's per-record page explains where the multiplication holds and where it breaks down.
Context: IBM's average cost of a healthcare breach is $6.64M in the 2026 report ($7.42M in 2025); the global average across all sectors was $4.44M in 2025.
Cost per record: method and limits / Healthcare breach cost, IBM 2026
Section F.6 / Notification clock
California statute and the HIPAA rule
State notification statute
California: Cal. Civ. Code 1798.82
- Notice to individuals
- Within 30 calendar days of discovery (effective 1 January 2026, SB 446)
- Attorney general threshold
- More than 500 California residents (Within 15 calendar days after notifying affected consumers)
- Private right of action
- Yes: Under CCPA Civ. Code 1798.150 for breaches from failure to maintain reasonable security; $107-$799 per consumer per incident (CPI-adjusted from $100-$750, effective Jan 2025)
- Penalty
- CCPA civil penalties of $2,663 per violation, $7,988 per intentional violation (CPI-adjusted, effective Jan 2025); CCPA private right of action for security-failure breaches
The HIPAA Breach Notification Rule runs alongside the state statute: notice to affected individuals and to HHS without unreasonable delay and no later than 60 days after discovery.
Section F.7 / Peer filings
California filings closest in size
Neighbours by size rank among California filings in 2024, topped up from other years where 2024 has too few. Filings of 10,000 or more link to their own page.
| Covered entity | Type | Individuals | Submitted | Breach type | Location | BA |
|---|---|---|---|---|---|---|
| Delta Dental of California | Health Plan | 7,056,189 | 5 Sep 2023 | |||
| Episource, LLCOpen | Business Associate | 6,725,572 | 6 Jun 2025 | |||
| Blue Shield of California | Business Associate | 4,700,000 | 9 Apr 2025 | |||
| Palomar Health Medical Group | Healthcare Provider | 1,140,221 | 3 Jul 2024 | |||
| Designed Receivable Solutions, Inc. | Business Associate | 585,035 | 23 Mar 2024 |
Index / Companion schedules
13 HHS breach register
→Hub: every filing, by state, year and entity.
04 Biggest breaches
→Mega-breaches with primary-source cost figures.
Industry / Healthcare
→IBM 2026: $6.64M average, 13 years at #1.
Regulation / HIPAA penalties
→OCR enforcement tiers and the 60-day rule.
11 50-state laws
→Deadline, AG threshold and penalties per state.
Cost / Per record
→Where the per-record model is reliable.
Provenance
Source: U.S. Department of Health and Human Services, Office for Civil Rights, Breach Portal (breaches affecting 500 or more individuals), retrieved 2026-08-28. Public domain. Individuals affected and dates as reported by the covered entity.
Portal: ocrportal.hhs.gov breach report. Statutory basis: HITECH Act section 13402(e)(4): the Secretary must post a list of breaches of unsecured protected health information affecting 500 or more individuals. Breaches affecting fewer than 500 individuals are reported to OCR annually and are not posted, so they are not on this register. Status wording follows the portal's two tabs ("Cases Currently Under Investigation" and "Archive") as of 28 August 2026; a filing moves to the archive when OCR closes the case. Modelled costs on this site are a method applied to the reported count, using IBM Cost of a Data Breach per-record figures, and are never a cost disclosed by the entity. This row: hhs-breach-archive__2026-08-28.csv, export row 1021.
Corrections: if you represent a listed entity and the portal row has been amended, email [email protected] with the portal entry and we will re-pull the export.