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    Software & AIAI / ML in DevicesSoftware LifecycleACP

    Algorithm Change Protocol

    The detailed procedural section of a PCCP that specifies how planned modifications to an AI/ML model will be developed, validated, and implemented.

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

    Definition

    An Algorithm Change Protocol (ACP) is one of three required components of a Predetermined Change Control Plan (PCCP) for AI/ML-enabled device software under FDA's 2024 final guidance. The ACP specifies the methodology for implementing the planned modifications described in the Description of Modifications: data management protocols, retraining triggers, performance evaluation methods, statistical analysis plans, acceptance criteria, update implementation procedures, transparency to users, and traceability. A well-constructed ACP is what lets manufacturers iterate on AI/ML models within an approved PCCP without filing supplements for each retrain.
    What the regulation says
    FDA's 2024 'Predetermined Change Control Plans for Machine Learning-Enabled Device Software Functions' guidance specifies ACP content expectations. The Description of Modifications, ACP, and Impact Assessment together constitute the PCCP.

    What this means in practice

    The ACP is the section of a PCCP where most of the technical and operational rigor lives. FDA reviewers focus on whether the ACP makes future changes predictable, evaluable, and traceable. Common ACP weaknesses include vague triggers ('when performance drifts'), missing acceptance criteria, no plan for handling subgroup performance degradation, and no specification of how user communication will be handled. A strong ACP often runs 30+ pages and is the centerpiece of the PCCP review.
    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?

    Primary references

    3 sources
    Link health: 1 verified 2 bot-blocked· last checked 2026-06-20
    FDA·2MDCG·1
    1. 1
      PCCP Guidance for ML-Enabled Devices (Final 2024)
      Bot-blocked
      FDAfda.gov
    2. 2
      MDCG Software Guidance
      Verified
      MDCGhealth.ec.europa.eu
    3. 3
      FDA - Software as a Medical Device (SaMD)
      Bot-blocked
      FDAfda.gov

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