How to write an FDA submission cover letter and reviewer guide

What should an FDA eCTD submission cover letter contain?

Identify the application, purpose, requested action and any FDA correspondence being answered. Reconcile the letter with the final package, then provide the applicable regulatory and technical descriptions, verified virus-check information and contacts. Use a separate submission reviewer guide when needed to explain the evidence and navigation without duplicating the eCTD contents.

Before you begin

FDA human-drug and biologic eCTD submissions. Special-purpose requests may have additional cover-letter wording; confirm the application and submission type first.

What you will prepare: A factual routing letter and, when useful, a separate submission-level reviewer guide.

Define the transaction before drafting

Write a working sentence: “This [application type and number] submission provides [purpose] in response to [dated request, if any] and requests [specific action].” Confirm each part against the submission plan and actual FDA correspondence. A protocol amendment, safety report and marketing application are different transactions even when they concern the same product.

For an IND, reconcile the sponsor and product with Form 1571 and the appropriate Part 312 amendment or report. For marketing submissions, reconcile the applicant and purpose with Form 356h. Do not call an amendment an original application or a response an approval request unless that is the actual action being sought. Unknown application type is undetermined; resolve it before choosing special wording or form selections.

Use a letter that answers the receiving reviewer’s questions

The v4 technical guide §3.1.1 recommends regulatory and technical descriptions, approximate submission size, a virus-free statement supported by the checking software’s name, version and company, and regulatory and technical contacts including email. Assemble these from the final publishing package, not last month’s template.

Editorial outline: recipient division; application/product identity; prominent submission purpose; dated FDA interaction being answered; brief contents and precise links; requested action; technical package description; factual virus-check information; responsible contacts; authorized execution under the organization’s process. A publishing owner must verify the scan before any virus-free assertion is signed. If evidence is missing, hold the assertion for confirmation rather than inventing a software version.

Put substantive answers and supporting reports in their appropriate dossier locations. The cover letter points to them; it should not become their only occurrence.

Create a separate map when the dossier needs one

For an original NDA, BLA or combination-product application, the technical guide describes a useful separate reviewer guide in 1.2. Explain how the dossier fits together: principal evidence, unusual organization, cross-referenced material and navigation to the requested review. An annotated table of “review question → document → location” is more useful than another copy of the eCTD table of contents.

This is a submission-level reviewer guide, not an SDRG or ADRG for study data. When patient experience data are submitted in a marketing application, use the guide’s §3.1.2 table to identify the types and actual dossier locations. Do not imply that an empty table establishes that no relevant data exist; have the evidence owners confirm the inventory.

Worked check: the response date is wrong

Fictional exercise: the cover letter says it answers a March request, but the response document addresses FDA’s June questions. Compare the original question list, response matrix and final sequence. Correct the reference and verify every hyperlink against the assembled package. Then change the scenario to an unsolicited amendment: remove the claim that FDA requested it and state its actual purpose. A missing FDA request cannot be repaired by copying a date from an earlier letter.

Build the letter from a claim-and-location sheet

Draft from the final submission facts, not the last letter’s prose. This internal worksheet gives each assertion an owner and makes the reviewer’s next action clear.

For a response package, prepare a second, small reviewer map: FDA question → response document and heading → supporting report → unresolved item, if any. Name the destination precisely enough that someone can find it without the hyperlink. Open each link in the assembled submission; a link that worked in the author’s shared drive is not a checked dossier link.

Writing exercise: “All comments have been addressed” overstates a package that answers four questions and requests clarification on a fifth. State that distinction in the transaction summary, identify the clarification requested, and direct the reviewer to the response matrix. If the submission is only part of an agreed response, describe its actual scope. Do not quietly drop the unanswered question from the map.

Keep scientific argument in the response or report. The letter should help a reviewer reach it, while the reviewer guide explains relationships among documents. Cross-check sponsor details with Form 1571, or applicant details with Form 356h, according to the transaction.

Frequently asked questions

Sources and revisions

Requirements, source recommendations and editorial preparation advice have different roles. Review the scope and revision of the source you use.

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