An eCTD FDA submission is a drug application filed to the Center for Drug Evaluation and Research or the Center for Biologics Evaluation and Research in the Electronic Common Technical Document format, using a defined five-module folder structure transmitted through the Electronic Submissions Gateway. The format is required for new drug applications, abbreviated new drug applications, biologics license applications, commercial investigational new drug applications, and every amendment, supplement, and referenced master file that follows.1U.S. Food and Drug Administration. Electronic Common Technical Document (eCTD) Congress authorized the mandate under Section 745A of the Federal Food, Drug, and Cosmetic Act, which also lets the FDA grant waivers and exemptions by rule.2Office of the Law Revision Counsel. 21 USC 379k-1 Electronic Format for Submissions
The Five-Module Structure
Every eCTD dossier is organized into the same five modules, whether the application is an NDA, ANDA, or BLA. The framework comes from the International Council for Harmonisation so one dossier can serve regulators in the United States, Europe, Japan, and other participating regions. Modules 2 through 5 are identical worldwide. Only Module 1 changes by country.
Module 1 is the U.S. administrative section. It carries the application forms (Form 356h for an NDA, Form 1571 for an IND), cover letters, patent and exclusivity information, financial disclosure certifications, meeting requests, fast track designation requests, pediatric study waivers and deferrals, dispute resolution correspondence, and draft labeling.3U.S. Food and Drug Administration. Comprehensive Table of Contents Headings and Hierarchy Because it is region-specific, none of it transfers directly to submissions filed with other regulators.
Module 2 holds the summaries and overviews of Modules 3, 4, and 5. Module 3 covers the drug substance and finished product: manufacturing processes, analytical methods, specifications, batch data, stability testing, and container closure systems. Module 4 contains the nonclinical study reports, including pharmacology, pharmacokinetics, and toxicology. Module 5, typically the largest section, contains the clinical study reports, statistical analyses, and patient-level datasets.
A design principle running through every module is granularity. Documents are broken into small discrete files inside a defined folder hierarchy, so a sponsor can update a single stability report or amend one clinical study without resubmitting the entire dossier.
Technical Specifications for File Preparation
Accepted File Formats
The eCTD does not require every document to be a PDF. The FDA accepts Word documents, Excel spreadsheets, XML files, image formats such as JPEG and PNG, and various modeling and simulation file types.4U.S. Food and Drug Administration. Specifications for File Format Types Using eCTD Specifications Most narrative documents and data summaries should also be provided as PDFs for archival purposes, and the file format guidance specifies which file types need that additional PDF archive copy.
PDF Requirements
PDFs must be version 1.4 through 1.7, PDF/A-1, or PDF/A-2, and readable by Adobe Acrobat X without plug-ins.5U.S. Food and Drug Administration. Portable Document Format (PDF) Specifications Fonts run 9 to 12 points, with 12-point Times New Roman recommended for narrative text and 9 to 10 points for tables. Non-standard fonts must be fully embedded. Any PDF longer than five pages needs a hyperlinked table of contents and bookmarks. Links that open another file should open in a new window, and all links should use relative paths rather than absolute drive references, or they break when the FDA loads the submission onto its servers. The initial view should display the bookmarks panel alongside the page.
The XML Backbone
Under eCTD version 3.2.2, an XML backbone file works as the automated table of contents for the whole submission. It uses a Document Type Definition to enforce the folder structure and file organization the FDA expects.6U.S. Food and Drug Administration. eCTD Backbone File Specification for Modules 2 Through 5 Each package carries metadata identifying the application number, applicant name, and submission type, which the FDA’s processing software uses to route and catalog the files.
Study Data Standards
Nonclinical datasets in Module 4 must follow the Standard for Exchange of Nonclinical Data (SEND) format. Studies starting after March 2022 must use SEND version 1.5, and developmental and reproductive toxicology studies starting after March 2023 require version 1.6.7U.S. Food and Drug Administration. FDA Data Standards Catalog Clinical datasets in Module 5 follow SDTM for tabulation data and ADaM for analysis data. The FDA may refuse to file an application that lacks them.
Requesting a Pre-Assigned Application Number
You need a pre-assigned application number before you can build the eCTD package, because the number goes into the folder structure and the XML backbone metadata. Request one through the CDER NextGen Portal or by secure email to the agency.8U.S. Food and Drug Administration. Requesting a Pre-Assigned Application Number An email request must include the applicant name as it will appear on the relevant FDA form, the applicant’s address, a U.S. contact with phone and email, and the drug name.
Submitting Through ESG NextGen
All electronic regulatory submissions reach the FDA through the Electronic Submissions Gateway Next Generation, the modernized platform that replaced the original ESG. It is the single entry point for secure submission, receipt, routing, and acknowledgment of regulatory documents.9U.S. Food and Drug Administration. Electronic Submissions Gateway Next Generation (ESG NextGen) The gateway does not open or review submissions; it acts as a conduit that routes each package to the appropriate FDA center based on selections you make during upload.
Setting up an account requires a valid digital certificate for each routing ID.10U.S. Food and Drug Administration. ESG NextGen AS2 Account Set-Up Steps The certificate verifies the sender’s identity and encrypts data in transit. Registration and compatibility testing take real time. Connectivity testing alone can run for days, so don’t leave gateway setup until the week you plan to file.
Acknowledgments and Technical Validation
After transmission, ESG NextGen issues a series of automated acknowledgments:
- ACK1 confirms whether the submission was successfully uploaded into ESG NextGen.
- ACK2 confirms whether it was successfully transmitted to the appropriate FDA center, when applicable.
- ACK3 and ACK4 carry the center’s response, including technical validation results, when applicable.
Not every submission type generates all four. For eCTD submissions to CDER, the system produces an ACK3 in PDF form containing the validation response.11U.S. Food and Drug Administration. Submission Acknowledgements
Validation Severity Levels
Under eCTD v4.0 validation criteria, the FDA sorts findings into two categories. A High Error is a serious technical problem that stops processing; the submission is treated as not received and must be fixed and resubmitted. A Warning flags something that could affect reviewability but does not automatically block acceptance, and gets forwarded to review staff for manual inspection.12U.S. Food and Drug Administration. Specifications for eCTD v4.0 Validation Criteria
Study Data Rejection Criteria
Specific technical rejection criteria apply to study data in Modules 4 and 5. Missing a required Trial Summary dataset triggers a high-severity rejection. Missing a demographic dataset or a define.xml file for clinical or nonclinical studies also forces resubmission.13U.S. Food and Drug Administration. Technical Rejection Criteria for Study Data These are among the most common technical failures that delay otherwise complete applications.
Refuse to File
Beyond technical validation, the FDA can refuse to file an NDA or BLA outright when the application is incomplete on its face. Common triggers include materially lacking or poorly organized content that prevents timely review, failure to submit required content electronically in the specified format, a missing environmental assessment, and reliance on a single clinical trial to demonstrate effectiveness when prior discussions with the agency established that more than one was needed.14U.S. Food and Drug Administration. Refuse to File – NDA and BLA Submissions to CDER Guidance for Industry A refuse-to-file decision resets the clock entirely.
Managing Lifecycle Sequences
An eCTD application is a living dossier. Every update, amendment, supplement, and report filed after the initial submission gets a sequential four-digit number. The first submission is 0001, the next is 0002, and so on.15U.S. Food and Drug Administration. eCTD Technical Conformance Guide Pre-submission information filed before the original application is coded as a “presubmission” and also begins at 0001. The conformance guide advises against jumping to high sequence numbers such as 9000, even if it seems organizationally convenient.
Within each sequence, lifecycle operators tell the FDA’s systems how new files interact with what’s already on record. Under v3.2.2 there are four:
- New introduces a document that didn’t previously exist in the dossier.
- Replace swaps an existing document with an updated version.
- Delete removes a document from the current view (the historical record is preserved).
- Append adds supplemental information to a previously submitted document.
These operators build a cumulative record where reviewers can trace the current version of any document without sorting through outdated files.
Transition to eCTD Version 4.0
As of September 2024, CDER and CBER accept new regulatory applications in eCTD v4.0.16U.S. Food and Drug Administration. Electronic Common Technical Document (eCTD) v4.0 The FDA has not announced a date when v4.0 becomes the only accepted format, and has said it will give advance notice before that point.1U.S. Food and Drug Administration. Electronic Common Technical Document (eCTD) For now v3.2.2 remains valid.
Version 4.0 is an architectural change, not an incremental update. The static XML backbone of v3.2.2 gives way to a dynamic message structure where only the headings relevant to a given sequence need to be submitted.17U.S. Food and Drug Administration. Electronic Common Technical Document (eCTD) v4.0 Technical Conformance Guide Other shifts change how you organize and manage content:
- Dynamic keywords replace fixed attributes and valid values. Document type keywords take over the role of file-tags, and sender-defined keywords let submitters create their own labels across applications.
- Documents sit under CTD headings through a “context of use” paired with keywords, forming a “context group.” When replacing a document, the context group must stay the same or the system rejects the replacement.
- A document already submitted in a separate application can be referenced by its unique identifier without being physically included again.
- Suspend replaces Delete as the way to inactivate content.
Sponsors with existing v3.2.2 applications do not need to resubmit their dossier when they start using v4.0. The v4.0 conformance guide sets out forward-compatibility rules for replacing or suspending v3.2.2 content within a v4.0 sequence.
User Fees and Review Timelines
Filing an NDA or BLA triggers substantial user fees under the Prescription Drug User Fee Act. For fiscal year 2026, running October 2025 through September 2026, the application fee for a submission requiring clinical data is $4,682,003. An application that does not require clinical data costs $2,341,002.18Federal Register. Prescription Drug User Fee Rates for Fiscal Year 2026 On top of the application fee, companies pay an annual prescription drug program fee of $442,213 per approved product.19U.S. Food and Drug Administration. Prescription Drug User Fee Rates for Fiscal Year 2026
Under PDUFA VII performance goals for fiscal years 2023 through 2027, the FDA targets completing 90 percent of standard reviews within 10 months and 90 percent of priority reviews within 6 months.20U.S. Food and Drug Administration. PDUFA Reauthorization Performance Goals and Procedures Fiscal Years 2023 Through 2027 For new molecular entity NDAs and original BLAs, the clock starts from the 60-day filing date rather than the receipt date. For non-NME NDAs and efficacy supplements, it runs from the date of receipt. Priority review designation cuts the timeline roughly in half.