--- title: "LTF, Letter to File | MedTech Terms" description: "Internal documentation justifying that a device change does not require a new 510(k) submission. 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Inadequate justification can result in a Form 483 observation or other enforcement actions." } } ] } ] } --- [ MedTech Terms The authoritative reference ](/) Browse Learn [Latest](/latest) About 1. [Home](/) 2. / 3. [Terms](/terms) 4. / 5. [Regulatory](/terms?cat=Regulatory) 6. / 7. Letter to File [All terms](/terms) Regulatory [Regulated Pathways](/ecosystems/regulated-pathways)LTF # Letter to File Internal documentation justifying that a device change does not require a new 510(k) submission. Reviewed by [Christian Espinosa, Founder, Blue Goat Cyber](/authors/christian-espinosa) Last reviewed May 5, 2026 ## 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). What the regulation says The FDA guidance "Deciding When to Submit a 510(k) for a Change to an Existing Device" provides criteria for when modifications require a new 510(k) submission versus when a Letter to File (LTF) is appropriate. Similarly, [ISO 13485](/terms/iso-13485):2016, clause 7.3.9, addresses control of design and development changes requiring documentation and verification. The EU [MDR](/terms/mdr-reporting), in Annex I, emphasizes the need to manage and document changes impacting safety and performance. Regulators expect comprehensive documentation justifying the decision not to submit a new premarket notification. ## 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. Common pitfalls - • 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 When is a Letter to File typically used? A Letter to File is used when a manufacturer determines that a change to a legally marketed device does not significantly alter its safety or effectiveness and therefore does not necessitate a new 510(k) submission to the FDA. What documentation should a Letter to File include? Can a Letter to File be challenged by regulators? ## Cross-references ### Used by Things that build on this term. - [ Change Control ](/terms/change-control) ### See also Closely related context worth reading. - [ 510(k) Premarket Notification(510(k)) ](/terms/510k) ## Related terms Grouped by theme ### Editor's picks · Hand-selected related concepts [ Regulatory 510(k) Premarket Notification(510(k)) FDA submission demonstrating a device is substantially equivalent to a legally marketed predicate. ](/terms/510k)[ Quality & Risk Design Controls Structured process governing the design of medical devices. ](/terms/design-controls)[ Quality & Risk FDA Form 483 Notice of inspectional observations issued at the conclusion of an FDA inspection. ](/terms/form-483) ### More in Regulatory · Same category [ Regulatory 510(k) Summary vs 510(k) Statement Two 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. ](/terms/510k-summary-vs-statement)[ Regulatory 513(g) Request for Information(513(g)) Formal mechanism to ask FDA whether a product is a device and, if so, its likely classification. ](/terms/513g)[ Regulatory Abbreviated 510(k) 510(k) variant that relies on FDA guidance, special controls, or recognized consensus standards. ](/terms/abbreviated-510k)[ Regulatory Accreditation Scheme for Conformity Assessment(ASCA) FDA voluntary program in which accredited testing labs perform standards-based testing accepted with reduced FDA scrutiny. ](/terms/asca) Cited by Where this term appears across MedTech Terms. Ecosystems (1) - [Regulated Pathways](/ecosystems/regulated-pathways) ## Primary references 3 sources Link health: 3 verified · last checked 2026-06-20 FDA· 2 RAPS· 1 1. [1 Deciding When to Submit a 510(k) for a Change Verified FDA · fda.gov ](https://www.fda.gov/regulatory-information/search-fda-guidance-documents/deciding-when-submit-510k-change-existing-device) 2. [2 RAPS Regulatory Focus Verified RAPS · raps.org ](https://www.raps.org/news-and-articles/news-articles) 3. [3 FDA - Medical Devices Verified FDA · fda.gov ](https://www.fda.gov/medical-devices) Inline markers like \[1\] jump to the matching reference above. Sponsor note ### Navigating an FDA or EU MDR submission? Blue Goat Cyber supports the cybersecurity content of premarket submissions, from threat models to the 524B narrative. [Book a 30-minute discovery session](https://go.bluegoatcyber.com/meetings/blue-goat-cyber/discovery-session) - No obligation - Expert-led from minute one - NDA available on request MedTech Terms is a community resource sponsored by [Blue Goat Cyber](https://bluegoatcyber.com). Definitions are independent of any vendor. On this term Category Regulatory Acronym LTF Sources 3 Updated 5/5/2026 [Compare with another term](/compare?a=letter-to-file) Learn in 60 seconds Card Lesson Quiz Internal documentation justifying that a device change does not require a new 510(k) submission. - · 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. Remember this Watch out: Failing to provide objective evidence and a robust scientific rationale for the decision is a common pitfall. Related terms - [510(k) Premarket Notification(510(k)) ](/terms/510k) - [Design Controls ](/terms/design-controls) - [FDA Form 483 ](/terms/form-483) You may also need Auto-suggested from Regulatory and shared keywords. - [Real-Time PMA Supplement Review ](/terms/pma-real-time-review) - [510(k) Summary vs 510(k) Statement ](/terms/510k-summary-vs-statement) - [AI Act Technical Documentation (Annex IV) ](/terms/ai-act-technical-documentation) - [Device Master File(MAF) ](/terms/device-master-file) - [Change Control ](/terms/change-control) - [De Novo Classification Request(De Novo) ](/terms/de-novo) [All Regulatory terms](/terms?cat=Regulatory) From the Blue Goat network Related resources and services on this topic. - [ MedTech Cybersecurity Standards Authoritative reference for the standards and guidances behind medical device cybersecurity. ](https://medtechcyberstandards.com) - [ MedTech Cybersecurity Crosswalk International crosswalk of medical device cybersecurity requirements across regulators. ](https://mdccrosswalk.com) - [ MedTech Truths Common misconceptions about medical device development - debunked. ](https://mdcmisconceptions.com) - [ MedTech Launchpad MedTech funding rounds, accelerators, and launch resources. ](https://medtechlaunchguide.com) MedTech Terms An authoritative, plain-language reference for the regulatory, quality, cybersecurity, and software terms that shape modern medical devices. 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