Least-burdensome, risk-based assurance — the CSA way.
We implement the FDA CSA operating model: per-requirement risk, right-sized test rigor across scripted, unscripted and vendor-evidence paths, and a defensible reduction in low-value testing. Ideal for teams re-baselining validation for velocity without giving up compliance.
Computer Software Assurance is FDA guidance, finalised in September 2025, on how much testing each requirement needs. Rather than uniform depth, effort follows the consequence of failure: scripted testing where a failure would reach a patient or a record, unscripted testing or assessed supplier evidence where it would not. The written rationale is what makes the reduction defensible.
Outcomes you can expect
- 30–60% reduction in scripted-test effort on Cat 3 systems
- Documented risk-to-test-strategy mapping
- Audit-defensible CSA rationale
Computer Software Assurance (CSA) is delivered by our validation & compliance services practice and — where it accelerates the outcome — augmented by our AI products: GxP Copilot for validation lifecycle work, and TraceDraft for clinical documentation.
Explore related capabilities: Computer System Validation (CSV), AI Validation (GxP AI / Annex 22), FDA 21 CFR Part 11 Compliance, EU Annex 11 & Annex 22 Compliance.
What FDA's Computer Software Assurance Guidance Actually Says
FDA's 2022 Computer Software Assurance guidance — formally titled 'Computer Software Assurance for Production and Quality System Software' — does not replace CSV. It reframes the goal: shift from documentation-heavy testing to critical thinking about what testing actually provides assurance. The guidance explicitly states that testing activities should be commensurate with the risk to product quality and patient safety. Where the risk is low, the testing burden should be lower. Where the risk is high, robust testing evidence is still required.
The guidance introduces the term 'assurance activities' as the umbrella: any activity that provides confidence that the software does what it is intended to do in a GxP context. Formal scripted testing is one such activity. Unscripted exploratory testing is another. Supplier-generated evidence — qualification documentation from the vendor — is a third. CSA asks the validation team to choose the right assurance activity for each requirement's risk level, rather than defaulting to full scripted testing across the board.
The Three Test Strategy Paths: Scripted, Unscripted, Supplier Evidence
Scripted testing — the traditional OQ and PQ approach — writes formal test cases before execution, records expected and actual results, and requires deviation documentation for every failure. It produces the most robust evidence but consumes the most resource. Under CSA, it is reserved for high-risk requirements: those where a failure would directly impact product quality, patient safety, or data integrity, and where the probability of failure is non-negligible. Per-requirement risk scoring, not system-level category alone, drives this decision.
Unscripted or exploratory testing documents a session charter and scope before execution, then records the tester's observations, findings, and pass/fail conclusion without pre-written test scripts. It is faster to prepare but still produces formal evidence that the function was tested. Supplier-provided evidence — vendor test reports, IQ documentation, release notes demonstrating pre-tested functions — can satisfy the assurance requirement for low-risk standard-configuration functions where the vendor has already demonstrated the behaviour. The validation team documents the rationale for leveraging supplier evidence, not just the evidence itself.
Where CSA Generates the Most Savings
The largest CSA savings come from Category 3 and Category 4 systems — pre-validated off-the-shelf software and configured products. A cloud-based SaaS LIMS from a qualified supplier has already been tested exhaustively by the vendor. Its standard configuration functions — sample login, result entry, report generation — have been executed thousands of times in customer environments. Writing scripted OQ test cases that re-prove the vendor's own tests on these functions adds documentation volume without adding assurance. CSA allows you to leverage the vendor's evidence for those functions and reserve your scripted testing budget for the configuration decisions unique to your implementation.
Category 5 custom systems still require rigorous testing under CSA — the FDA guidance is explicit that critical custom code must be tested commensurate with its risk. The savings in Category 5 come from right-sizing test case scope at the requirement level rather than writing a test for every function irrespective of risk. A high-risk calculation algorithm gets exhaustive boundary value tests. A low-risk administrative function gets a spot check. The per-requirement risk score justifies both decisions in the same document.
CSV vs CSA: The Practical Differences
In practice, the difference between CSV and CSA is not a different regulatory standard — it is a different default decision. Under traditional CSV, the default is scripted testing unless there is a specific documented reason to do less. Under CSA, the default is the minimum assurance activity sufficient for the risk level, with scripted testing requiring a positive risk justification. The same GxP-critical system requires the same regulatory outcome: documented assurance that it works. CSA changes how you get there.
The documentation differences are also substantive. A CSA approach produces a risk assessment that maps every requirement to a risk score and a test strategy — visible reasoning rather than a template. The assurance summary explains why each requirement received its strategy. A traditional CSV approach produces voluminous test scripts that demonstrate execution without always demonstrating reasoning. Inspectors who understand CSA look for the reasoning; those trained on traditional CSV look for the volume. Our CSA deliverable set is structured to satisfy both.
Implementing CSA: Re-Baselining an Existing Validated Estate
Transitioning an existing CSV-validated estate to CSA is a re-baselining exercise. It begins with a risk assessment of the system's requirements against the CSA framework, identifying where current scripted test coverage is genuinely risk-justified and where it represents low-value testing that CSA would permit to be replaced by unscripted or supplier evidence approaches. The output is a revised validation strategy — not a replacement of the existing validation — that documents the rationale for each change in approach.
Re-baselining does not require re-executing all tests. It requires documented reasoning that the existing validation provides adequate assurance, supplemented where gaps exist. For systems with annual periodic review cycles, the re-baseline can be performed as part of the periodic review without triggering a standalone revalidation. Our CSA re-baselining service typically reduces ongoing maintenance burden by 30–50% for Category 3 and 4 systems while producing a more defensible, reasoning-led validation package than the original CSV approach delivered.
See it on your own data. In 30 minutes.
Bring a system, a URS, or an AE listing. We'll show you how GxP Copilot and TraceDraft compress the validation and clinical documentation cycle without compromising Part 11 or Annex 22 posture.