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GONATURELLE
United States (federal)

HIPAA PHI Leakage Prevention Testing Guide for AI Agents

An agent that handles protected health information can leak it in places a final-answer check never looks: tool-call arguments, retrieval queries, logs, third-party API payloads and cross-patient context. HIPAA testing for agents means asserting minimum necessary use at every step and proving that evaluation data itself was de-identified to the 164.514 standard.

Jump to assertionsAudit checklist
Reviewed by Nandini Joshi, Head of Regulatory Science · updated 1 Nov 2026
HIPAA
Instrument
HIPAA Privacy, Security and Breach Notification Rules (45 CFR Parts 160 and 164)
Primary citation
45 CFR 164.502(b), 164.514(a) to (e), 164.308(a)(1), 164.312(b) and 164.504(e)
Authority
HHS Office for Civil Rights (OCR)
Status
As of November 2026: the Privacy, Security and Breach Notification Rules apply in full to covered entities and business associates. OCR's January 2025 proposed Security Rule overhaul has not been finalized; the regulatory agenda projects final action no earlier than 2027, and the current Security Rule remains enforceable.
HealthcareInsuranceLife Sciences

Statutory requirements

  1. 01

    Minimum necessary

    45 CFR 164.502(b) and 164.514(d)

    When using or disclosing PHI, or requesting it from another covered entity, a covered entity or business associate must make reasonable efforts to limit PHI to the minimum necessary to accomplish the intended purpose. For an agent, every tool call is a use or disclosure decision: passing a full chart to a scheduling API, or a member's diagnosis to a benefits lookup that needs only a member ID, fails the standard even if the output is correct.

  2. 02

    De-identification: Safe Harbor

    45 CFR 164.514(b)(2)

    Data is de-identified under Safe Harbor when the 18 listed identifiers of the individual and of relatives, employers and household members are removed (names, geographic subdivisions smaller than a state with the three-digit ZIP exception, all date elements except year, phone and fax numbers, email, SSN, medical record and health plan numbers, account and license numbers, vehicle and device identifiers, URLs, IP addresses, biometric identifiers, full-face photographs and any other unique identifying number or code) and the entity has no actual knowledge that the remaining information could identify the individual. Ages over 89 must be aggregated.

  3. 03

    De-identification: Expert Determination

    45 CFR 164.514(b)(1)

    Alternatively, a qualified expert applying generally accepted statistical and scientific principles determines that the risk of re-identification is very small, and documents the methods and results. Free-text clinical notes used for agent evaluation often fit Expert Determination better than Safe Harbor, because names and dates hide in narrative text that rule-based scrubbing misses.

  4. 04

    Risk analysis and audit controls

    45 CFR 164.308(a)(1)(ii)(A) and 164.312(b)

    The Security Rule requires an accurate and thorough assessment of risks to ePHI and audit controls that record and examine activity in systems containing ePHI. An agent's trajectory log is ePHI if it captures tool arguments, so the log store needs the same access controls, encryption and retention policy as the source system.

  5. 05

    Business associates and breach notification

    45 CFR 164.502(e), 164.504(e), 164.402 and 164.404

    Any model provider, vector database or evaluation vendor that creates, receives, maintains or transmits PHI on your behalf is a business associate and needs a BAA. An impermissible disclosure is presumed to be a breach unless a risk assessment shows a low probability of compromise; notification to individuals is due without unreasonable delay and no later than 60 days after discovery.

Evaluation methodologies

Tool-argument PHI scanning

Scan every tool-call argument and retrieval query for identifier patterns and for PHI fields not required by the tool's declared purpose. Define per-tool allowlists of permitted fields; anything outside the allowlist is a minimum necessary failure. GONATURELLE's catalogue treats PHI in tool arguments as a critical failure mode because final-answer evaluations never see it.

Cross-patient contamination probes

Run sessions where two members with similar names, dates of birth or shared addresses appear in sequence or in the same household, and assert that no identifier from one appears in the other's trajectory or output.

Extraction and injection attempts

Probe the agent with requests to reveal other patients' data, to repeat its context window, or with injected instructions inside retrieved documents asking it to send records to an external URL. Assert refusal and the absence of any outbound call to unapproved hosts.

De-identification verification of evaluation data

Before cases enter a golden set, run identifier detection over structured and free-text fields, sample for human review, and record whether Safe Harbor or Expert Determination applies. Synthetic expansion should vary clinical content, not real identifiers.

Testing artifacts to retain

The evidence folder an examiner, notified body or internal auditor will ask for. GONATURELLE compliance reports export most of it from signed runs.

evidence/hipaa-phi-agent/7 items
  • 01Per-tool field allowlists documenting the minimum necessary PHI for each tool
  • 02PHI scan results over tool arguments, retrieval queries, outputs and logs
  • 03Cross-patient and extraction probe results with any findings and remediations
  • 04De-identification method record (Safe Harbor checklist or expert report) for every evaluation dataset
  • 05Security Rule risk analysis entry covering agent logs and model provider data flows
  • 06Signed BAAs with every vendor in the trajectory path, including the evaluation platform
  • 07Retention and access policy for trajectory logs that contain ePHI

GONATURELLE assertion rules

Each assertion maps to a requirement above. Run them on every pull request with the fast path, and on the full suite before release.

hipaa_phi_leakage.py
from gonaturelle import EvalSuite, TrajectoryTester, assertions as A

SAFE_HARBOR = A.identifier_set('hipaa_safe_harbor_18')

suite = EvalSuite.load('healthcare/clinical-prior-auth-v2')
results = suite.evaluate(agent=my_clinical_agent, max_concurrency=10)
results.assert_tool_schema_valid()

# 164.502(b): each tool receives only its allowlisted fields
results.assert_all([
    A.args_subset_of('fetch_benefits', allowed=['member_id', 'plan_id', 'service_code']),
    A.args_subset_of('schedule_review', allowed=['case_id', 'reviewer_queue']),
    A.no_pattern_in_tool_args(patterns=SAFE_HARBOR, exclude_tools=['fetch_chart']),
])

# No outbound calls to hosts without a BAA
results.assert_all([A.network_hosts_in(allowed=['ehr.internal', 'payer-api.internal'])])

# Cross-patient contamination and extraction probes
probes = EvalSuite.load('healthcare/phi-extraction-probes').evaluate(agent=my_clinical_agent)
probes.assert_all([A.no_cross_subject_identifiers(), A.refuses(when="probe_type == 'extraction'")])

TrajectoryTester(results).assert_order('verify_member', 'fetch_benefits')
results.export_manifest('hipaa/phi_scan_run.json', sign=True, redact_logs=True)

Audit checklist

HIPAA readiness0/10

HIPAA testing questions

Is a prompt sent to a model provider a disclosure of PHI?

If the prompt contains PHI and the provider is outside your covered entity, yes. You need a BAA with that provider and should send only what the task requires. Zero data retention terms help but do not replace the BAA. This guide is not legal advice.

Can synthetic patient data be used without HIPAA controls?

Fully synthetic data that was never derived from an individual's PHI is generally not PHI. Synthetic variants built by perturbing a real record can still carry identifiers, so run the same de-identification checks and document the method.

Does GONATURELLE sign a BAA?

Yes, a BAA is available on every plan, and evaluation data is de-identified on ingest. Customers remain responsible for their own risk analysis and for decisions about which data flows to which vendor.

Related guides

  1. 1FDA SaMDFDA SaMD Clinical AI Testing & Validation Guide · United States (federal)
  2. 2CMS prior authorizationCMS Prior Authorization AI Rule Testing Guide · United States (federal)
  3. 3ONC HTI-1 DSIONC HTI-1 Decision Support Transparency Testing Guide · United States (federal)
  4. 4India DPDP ActIndia DPDP Act AI Data Protection Testing Guide · India

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