Submission & ApprovalLast reviewed April 2026

Complete Response Letter(CRL)

An FDA letter indicating that an application review is complete but the application is not approved as submitted.

Usage Examples

The company received a CRL citing manufacturing deficiencies.
The CRL requested an additional Phase 3 trial.
Following the CRL, the sponsor requested a Type A meeting.

What is CRL?

A Complete Response Letter (CRL) is issued by FDA when the review of an NDA, BLA, or ANDA is complete but the application cannot be approved in its present form. The CRL identifies all deficiencies that must be addressed before approval can be granted.

CRLs may cite deficiencies in clinical data, CMC/manufacturing, labeling, facilities, or other aspects of the submission. The sponsor must respond with amendments, additional data, or clarifications. Serious deficiencies may require new clinical trials.

Upon receiving a CRL, sponsors have options including resubmission to address deficiencies, requesting a meeting with FDA, withdrawing the application, or requesting a hearing. Resubmission triggers a new review clock (typically 2-6 months depending on response scope).

Regulatory Context

This term appears most often in submission & approval workflows where submission quality, regulatory evidence, and audit readiness depend on consistent language. It is commonly referenced alongside 21 CFR 314 110, 21 CFR 601 3.

FDAICHEMA

When This Matters

The company received a CRL citing manufacturing deficiencies.
The CRL requested an additional Phase 3 trial.
Following the CRL, the sponsor requested a Type A meeting.

Common Mistakes

Treating submission readiness as a formatting-only check without lifecycle validation.
Using outdated guidance references across modules and summaries.
Missing cross-functional review between RA, CMC, and quality before submission.

Related Regulations

21 CFR 314 11021 CFR 601 3

How to Respond to a Complete Response Letter

Address FDA's cited deficiencies in a CRL and resubmit the NDA or BLA for approval.

1
Analyze the CRL systematically
Parse each cited deficiency: what FDA is asking for, what evidence would resolve it, whether new studies are required or reanalysis suffices. Classify deficiencies by effort required: administrative, CMC, clinical, statistical.
2
Request a Type A meeting with FDA
Type A meetings are scheduled fast (within 30 days) specifically for CRL clarification. Use the meeting to confirm interpretation of deficiencies, agree on response scope, and avoid misalignment during preparation.
3
Develop the response strategy
For each deficiency, identify the specific remediation: new analyses of existing data, additional clinical studies, CMC changes, labeling modifications, or risk management additions. Build a timeline.
4
Execute required studies or analyses
Conduct additional nonclinical, clinical, or statistical work as needed. This can range from weeks (re-analyses) to 18+ months (new Phase 3 confirmatory trial). Timeline-critical decisions drive resubmission classification.
5
Classify the resubmission
FDA classifies resubmissions as Class 1 (2-month review) or Class 2 (6-month review) based on content. Minor clarifications are Class 1; substantial new clinical data is Class 2. The classification is agreed with FDA during preparation.
6
Submit the Complete Response
File the response as an NDA/BLA amendment via eCTD + ESG. Organize the response mirroring FDA's CRL deficiency structure for reviewer navigation. Pay any applicable additional user fee.
7
Support Class 1 or Class 2 review
FDA review begins on the resubmission filing date. Respond to any Information Requests during review. Approval or second CRL issues at the new PDUFA action date.

Frequently Asked Questions

Common causes include clinical efficacy concerns, safety issues, CMC/manufacturing deficiencies, labeling problems, facility inspection findings, or insufficient data to support approval.

Sponsors typically resubmit with amendments addressing all deficiencies. They may first request a Type A meeting to clarify requirements. Minor issues may be resolved quickly; major issues may require new studies.

Responses are classified as Class 1 (2-month review) or Class 2 (6-month review) depending on the scope of new information. Major amendments with new clinical data typically receive 6-month review.