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    Algorithm Change Protocol

    Historical FDA AI/ML change-control terminology, now reflected in the PCCP Modification Protocol.

    Reviewed by Christian Espinosa, Founder, Blue Goat CyberLast reviewed June 20, 2026

    Definition

    Algorithm Change Protocol (ACP) is terminology from FDA’s 2019 proposed AI/ML framework, not the component name in current final guidance. The August 18, 2025 final PCCP guidance, originally issued December 4, 2024, describes three components: Description of Modifications, Modification Protocol, and Impact Assessment. The Modification Protocol covers data management, retraining practices, performance evaluation, and update procedures. Only modifications consistent with the FDA-authorized PCCP may be implemented without an otherwise required new marketing submission. No standard 30-page length is specified.
    What the regulation says
    Algorithm Change Protocol (ACP) is terminology from FDA’s 2019 proposed AI/ML framework, not the component name in current final guidance. The August 18, 2025 final PCCP guidance, originally issued December 4, 2024, describes three components: Description of Modifications, Modification Protocol, and Impact Assessment. The Modification Protocol covers data management, retraining practices, performance evaluation, and update procedures. Only modifications consistent with the FDA-authorized PCCP may be implemented without an otherwise required new marketing submission. No standard 30-page length is specified.

    What this means in practice

    Algorithm Change Protocol (ACP) is terminology from FDA’s 2019 proposed AI/ML framework, not the component name in current final guidance. The August 18, 2025 final PCCP guidance, originally issued December 4, 2024, describes three components: Description of Modifications, Modification Protocol, and Impact Assessment. The Modification Protocol covers data management, retraining practices, performance evaluation, and update procedures. Only modifications consistent with the FDA-authorized PCCP may be implemented without an otherwise required new marketing submission. No standard 30-page length is specified.

    Examples

    • Illustrative: An ACP for an AI-powered diagnostic imaging tool would detail the specific data drift thresholds that trigger model retraining and the statistical methods used to validate new versions against a predefined ground truth dataset.
    • Illustrative: For a continuous glucose monitor with an adaptive algorithm, the ACP would describe how patient-specific data will be used to retrain the model, the frequency of such retraining, and the performance metrics required for approval of the updated algorithm.
    • Illustrative: A medical device using an AI model to detect anomalies in physiological signals would have an ACP outlining the process for incorporating newly identified anomaly patterns, including data collection, model update procedures, and post-update performance monitoring.
    Common pitfalls
    • •Treating the ACP as a high-level outline, FDA expects specific protocols with quantitative criteria.
    • •Omitting subgroup analysis methodology, disparate performance changes across patient subgroups are a focus area.
    • •Failing to specify rollback procedures, what happens when an update doesn't meet acceptance criteria in production?

    Frequently asked questions

    Algorithm Change Protocol (ACP) is terminology from FDA’s 2019 proposed AI/ML framework, not the component name in current final guidance. The August 18, 2025 final PCCP guidance, originally issued December 4, 2024, describes three components: Description of Modifications, Modification Protocol, and Impact Assessment. The Modification Protocol covers data management, retraining practices, performance evaluation, and update procedures. Only modifications consistent with the FDA-authorized PCCP may be implemented without an otherwise required new marketing submission. No standard 30-page length is specified.

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    Sources

    3 sources

    Sources support the definition or relevant regulatory context, not necessarily every claim on this page. Each is graded against our source-tier hierarchy so you can see what rests on binding law versus commentary.

    Official-source claim check:

    ACP is historical 2019 terminology. Current final PCCP guidance uses Modification Protocol, alongside Description of Modifications and Impact Assessment.

    Partial review: verified corrections are applied, but this is not a full accuracy certification. The last full review date is unchanged.

    Remaining verification limits
    • Original merged record reviewed in full. Illustrative examples are hypothetical, not verified case histories. Evidence supports the specific propositions below, not an assertion that every linked page verifies all merged content.
    Tier 2Regulator guidance and consensus· 3
    Link health: 2 verified 1 unchecked· last checked 2026-06-20· added official documents checked 2026-11-01
    U.S. Code·1MDCG·1FDA·1
    1. 1
      FD&C Act section 515C (21 U.S.C. 360e-4), PCCPs
      Tier 2 Unchecked
      U.S. Codefda.gov
    2. 2
      MDCG Software Guidance
      Tier 2 Verified
      MDCGhealth.ec.europa.eu
    3. 3
      FDA - Software as a Medical Device (SaMD)
      Tier 2 Verified
      FDAfda.gov

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