Letter to File
Internal documentation justifying that a device change does not require a new 510(k) submission.
Definition
A Letter to File is a manufacturer-prepared rationale, retained in the device's design history, explaining why a change does not significantly affect safety or effectiveness and therefore does not trigger a new 510(k). The decision follows the flowcharts in FDA's 2017 guidance 'Deciding When to Submit a 510(k) for a Change to an Existing Device' and its software-specific companion. Supporting verification and validation should sit with the rationale in the quality system records. FDA may review these during inspections and disagree with the conclusion.What this means in practice
FDA's 'Deciding When to Submit a 510(k) for a Change' guidance provides flowcharts. LTFs are scrutinized during inspections; weak rationales are a common Form 483 finding.Examples
- A manufacturer makes a minor change to the color of a device's casing without altering its material, function, or performance, documenting this decision with a Letter to File.
- An update to a device's software primarily improves user interface aesthetics without affecting any clinical algorithms or safety features, justified by an LTF.
- A supplier change for a non-critical component where the new component is shown to be functionally equivalent and poses no new risks, documented via a Letter to File.
- •Failing to provide objective evidence and a robust scientific rationale for the decision is a common pitfall.
- •Inaccurately assessing the impact of a change on device safety or effectiveness can lead to regulatory non-compliance.
- •Not obtaining necessary expert reviews or management approvals for the Letter to File can be a critical error.
- •Treating a Letter to File as a routine administrative task rather than a critical regulatory decision is a common mistake.
- •Neglecting to update relevant risk management files (e.g., in accordance with ISO 14971:2019) after a change is a significant oversight.
Frequently asked questions
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Related terms
Grouped by themeEditor's picks
· Hand-selected related conceptsFDA submission demonstrating a device is substantially equivalent to a legally marketed predicate.
Structured process governing the design of medical devices.
Notice of inspectional observations issued at the conclusion of an FDA inspection.
More in Regulatory
· Same categoryTwo alternative disclosure mechanisms in a 510(k) submission, a Summary is public on FDA's website; a Statement promises to share Safety & Effectiveness info on request.
Formal mechanism to ask FDA whether a product is a device and, if so, its likely classification.
510(k) variant that relies on FDA guidance, special controls, or recognized consensus standards.
FDA voluntary program in which accredited testing labs perform standards-based testing accepted with reduced FDA scrutiny.
Where this term appears across MedTech Terms.
Sources
3 sourcesSources 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.
- 1Deciding When to Submit a 510(k) for a ChangeTier 2 VerifiedFDAfda.gov
- 2RAPS Regulatory FocusTier 4 VerifiedRAPSraps.org
- 3FDA - Medical DevicesTier 2 VerifiedFDAfda.gov
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