Filing an IND: Application to 30-Day Clock

Last verified: August 16, 2026, directly against 21 CFR Part 312 (Subparts B and C, via the Cornell Legal Information Institute e-CFR mirror) — specifically 21 CFR 312.23 (IND content and format), 312.40 (general requirements / when an IND goes into effect), and 312.42 (clinical holds and requests for modification). Regulatory text changes infrequently but not never; re-check the current 21 CFR Part 312 text if you are reading this more than a year or two later.

The IND filing sequence at a glance

Stage	What happens	Clock / trigger
1. Pre-IND (optional)	Sponsor requests a Type B pre-IND meeting with the review division to surface nonclinical, CMC, and protocol-design problems before filing.	No regulatory deadline; sponsor-initiated. See CASRAI’s Pre-IND Meeting guide.
2. Assemble the IND	Sponsor compiles the content required under 21 CFR 312.23(a): Form FDA 1571 cover sheet, table of contents, introductory statement and general investigational plan, investigator’s brochure, clinical protocol, chemistry/manufacturing/controls (CMC) data, pharmacology and toxicology data, and prior human experience.	No deadline — sponsor-controlled.
3. Submit the IND	Complete package filed with the relevant FDA review division, almost always electronically via the FDA Electronic Submissions Gateway (ESG) in eCTD format.	Day 0: FDA notifies the sponsor in writing of the date it received the IND (21 CFR 312.40(b)).
4. FDA safety review	The review division (clinical, pharm/tox, and CMC reviewers) evaluates whether the proposed studies expose subjects to unreasonable risk.	Runs concurrently with the 30-day clock — there is no separate “review period” distinct from the waiting period itself.
5. The 30-day clock resolves	Either FDA notifies the sponsor of a clinical hold under 21 CFR 312.42, or the clock simply expires with no FDA action.	30 calendar days after FDA’s date of receipt (21 CFR 312.40(b)(1)).
6. IND goes into effect	The sponsor may ship the investigational drug to investigators and begin dosing human subjects — unless a clinical hold is in place.	Automatic on day 30 (or earlier, if FDA affirmatively authorizes the study sooner, per 312.40(b)(2)).

Filing intent: what this page covers

This guide walks through the full mechanics of filing an Investigational New Drug (IND) application with FDA under 21 CFR Part 312 — what the submission must contain, how and where it is filed, how the 30-calendar-day “safe to proceed” waiting period works, and what a clinical hold means if FDA acts before that clock runs out. It is written for the research administrator or investigator assembling (or supporting) an IND submission, not for a specific therapeutic area. Two related, narrower CASRAI pages cover pieces of this process in more depth: the Pre-IND Meeting guide covers the optional consultation that typically happens before filing (a Type B meeting — see CASRAI’s FDA meeting types guide), and the FDA Form 1571 guide covers just the cover-sheet form in field-by-field detail. This page is the end-to-end process those two pages sit inside. For how an IND relates to the device equivalent, see CASRAI’s IND vs. IDE comparison; for where filing sits relative to the rest of a trial’s lifecycle, see Clinical Trial Phases and the IRB/REC approval process, which runs in parallel with, but independently of, the FDA pathway.

What FDA requires an IND to contain (21 CFR 312.23(a))

An IND is not a single form — it is an assembled package. Per 21 CFR 312.23(a), a complete initial IND must include, in order:

• Cover sheet (Form FDA 1571). Identifies the sponsor, the drug, the phase(s) of investigation, and contains the sponsor’s required regulatory commitments — including the commitment not to begin clinical investigations until the IND is in effect, and that an IRB compliant with 21 CFR Part 56 will review and approve the study. See CASRAI’s dedicated Form 1571 guide for a field-by-field walkthrough.
• Table of contents.
• Introductory statement and general investigational plan. Identifies the drug and its pharmacological class, formulation, and route of administration; summarizes prior human experience (including relevant experience in other countries); discloses any prior withdrawal from investigation or marketing for safety/effectiveness reasons; and lays out the general plan for investigating the drug over the coming year.
• Investigator’s brochure (for a commercial/company-sponsored IND; an investigator-sponsor filing for their own study may satisfy this differently, per 312.23(a)(5)).
• Clinical protocol(s) for the proposed study or studies.
• Chemistry, manufacturing, and controls (CMC) information describing the drug substance, drug product, and controls used to ensure identity, strength, quality, and purity.
• Pharmacology and toxicology information — the nonclinical data supporting the conclusion that the drug is reasonably safe for the proposed initial human testing, generated under Good Laboratory Practice (GLP, 21 CFR Part 58) where applicable. See also CASRAI’s IND-Enabling Studies entry.
• Previous human experience with the drug, including experience from outside the United States.
• Additional information as applicable — e.g., drug dependence/abuse potential data, radioactive drug data, or other information FDA specifically requests.

An Investigator IND — filed by a physician who both initiates and conducts the investigation, the common structure for institutional/investigator-initiated FDA-regulated research — follows the same 312.23(a) content list, though the investigator’s-brochure and CMC sections are frequently thinner where the drug is already commercially available and the investigation is studying a new use, dose, or population rather than a novel compound. Not every use of an investigational drug requires a full IND in the first place — see CASRAI’s IND Exemption (21 CFR 312.2(b)) entry for the criteria.

Where and how an IND is filed

The complete package goes to the FDA review division responsible for the relevant therapeutic area — typically within the Center for Drug Evaluation and Research (CDER) or the Center for Biologics Evaluation and Research (CBER), depending on whether the product is a drug or a biologic. Submissions are made electronically through the FDA Electronic Submissions Gateway (ESG), structured in eCTD (electronic Common Technical Document) format. Commercial IND submissions have been required to use eCTD format since May 2018; noncommercial/investigator-sponsored INDs are exempt from that mandate but are encouraged to submit electronically. Every submission under an IND — not just the original filing — is accompanied by a Form FDA 1571 and receives a sequential serial number, starting at 0000 for the original application.

The 30-day clock: how “safe to proceed” actually works

This is the part of the process that most often gets described loosely, so it’s worth being precise about what 21 CFR 312.40(b) actually says. An IND goes into effect — meaning the sponsor may ship investigational drug to named investigators and dosing may begin — on whichever of these happens first:

1. Thirty calendar days after FDA receives the IND, unless FDA notifies the sponsor before then that the study is subject to a clinical hold; or
2. Earlier notification from FDA that the clinical investigations described in the IND may begin.

FDA notifies the sponsor in writing of the date it received the IND — that date is day zero of the 30-day count. There is no separate “approval letter” that arrives on day 30 in the way there is with, for example, an NDA approval or Health Canada’s Clinical Trial Application (which uses an affirmative No Objection Letter model rather than FDA’s default-permission model — see the comparison note below). If FDA takes no action within 30 calendar days, the IND simply goes into effect by operation of the regulation itself. This is sometimes called the IND being “safe to proceed,” though that exact phrase does not appear in the regulatory text — it is a description sponsors and regulatory professionals use for the state of an IND that has cleared the 30-day window without a hold.

The same 30-day threshold governs when the sponsor may physically ship the investigational drug to investigators (312.40(c)) — shipping and dosing are gated by the identical clock, not by two separate timelines.

Clinical holds: grounds, notice, and how they’re resolved

A clinical hold is an FDA order to delay a proposed study or suspend an ongoing one (21 CFR 312.42(a)). If a proposed study is placed on hold, no subjects may be given the investigational drug; if an ongoing study is placed on hold, no new subjects may be enrolled and existing subjects generally must be taken off the investigational drug (unless FDA specifically permits continuation in the interest of patient safety).

FDA may place a Phase 1 study on clinical hold under 312.42(b)(1) if it finds, among other grounds, that:

• Human subjects are or would be exposed to an unreasonable and significant risk of illness or injury;
• The named clinical investigators are not qualified by training and experience to conduct the study;
• The investigator’s brochure is misleading, erroneous, or materially incomplete;
• The IND does not contain sufficient information under 312.23 to assess the risk to subjects; or
• The study of a drug for a life-threatening disease affecting both sexes improperly excludes men or women with reproductive potential because of a reproductive/developmental toxicity risk (with specific, narrow exceptions in the regulation for single-sex studies).

For Phase 2 or 3 studies, all of the above grounds apply, plus FDA may hold a study whose plan or protocol is “clearly deficient in design to meet its stated objectives” (312.42(b)(2)). Separate, narrower grounds apply specifically to expanded-access INDs and treatment protocols (312.42(b)(3)).

Procedurally: where patients are not at immediate serious risk, FDA will typically try to discuss and resolve a suspected deficiency with the sponsor before issuing a hold (312.42(c)). If FDA proceeds, the hold order may be issued by phone or in writing and identifies the specific studies affected; the review division’s Director must follow up with a written explanation of the basis for the hold within 30 calendar days of imposing it (312.42(d)). To lift a hold, the sponsor submits a written request plus a complete response to the deficiencies cited, and FDA must respond in writing within 30 calendar days of receiving that complete response — either lifting or maintaining the hold, with reasons stated (312.42(e)). A sponsor may not resume the study until FDA has actually notified it that the hold is lifted, regardless of how that 30-day response clock runs. A sponsor who disagrees with a hold may request reconsideration under 21 CFR 312.48 (312.42(f)). If every study under an IND remains on clinical hold for a full year or more, FDA may place the IND itself on inactive status (312.42(g)).

Filing an IND vs. a comparable non-US pathway

FDA’s IND process is a default-permission model: the sponsor may proceed once the 30-day window closes without an FDA-imposed hold, and no explicit “go” letter is required. This is structurally different from, for example, Health Canada’s Clinical Trial Application (CTA) process, which is an affirmative-authorization model — a sponsor may only proceed once Health Canada actually issues a No Objection Letter (NOL), not simply because a review window has elapsed. Sponsors running multi-country trials should not assume the two clocks behave the same way procedurally even where the review windows are numerically similar. For the parallel US device pathway, see CASRAI’s IND vs. IDE comparison.

After the IND is in effect: ongoing submissions

Filing does not end at day 30. Sponsors remain obligated to submit expedited IND Safety Reports under 21 CFR 312.32 for unexpected fatal or life-threatening events and other qualifying findings, and a required IND Annual Report summarizing the year’s progress, for as long as the IND remains active. Each participating investigator also completes a Form FDA 1572 (Statement of Investigator); see CASRAI’s field-by-field Form 1572 guide for how to complete it correctly.

Filing checklist

• Confirm whether a pre-IND meeting is warranted (novel mechanism, first-in-class modality, or a nonclinical/CMC package with real judgment calls) — see the Pre-IND Meeting guide.
• Assemble all 312.23(a) components in the required order; confirm the CMC and pharm/tox packages are complete enough to withstand a 312.42(b)(1)(iv) sufficiency challenge.
• Complete Form FDA 1571 in full, with correct sponsor identification and required commitments — see the Form 1571 guide.
• If the study will enroll named investigators at the outset, prepare each investigator’s Form FDA 1572 (Statement of Investigator) in parallel.
• Submit electronically via the FDA Electronic Submissions Gateway in eCTD format (required for commercial INDs since May 2018; encouraged for noncommercial/investigator-sponsored INDs).
• Record FDA’s written notice of the date of receipt — that date starts the 30-calendar-day clock.
• Do not ship investigational drug or dose any subject before day 30 unless FDA affirmatively authorizes an earlier start.
• If a clinical hold notice arrives, do not proceed under any circumstance until FDA has notified the sponsor in writing that the hold is lifted — the 30-day response clock on a hold-removal request does not itself authorize resumption.

Frequently Asked Questions

How do I file an IND?

Assemble the content required under 21 CFR 312.23(a) — cover sheet (Form FDA 1571), investigational plan, investigator’s brochure, protocol, CMC data, pharmacology/toxicology data, and prior human experience — and submit the complete package to the relevant FDA review division, almost always electronically through the FDA Electronic Submissions Gateway in eCTD format. FDA then has 30 calendar days from its date of receipt to place the study on clinical hold; if it does not, the IND goes into effect automatically.

What is the IND 30-day safe-to-proceed rule?

Under 21 CFR 312.40(b), an IND goes into effect 30 calendar days after FDA receives it, unless FDA notifies the sponsor before then that the proposed study is subject to a clinical hold under 21 CFR 312.42. “Safe to proceed” is shorthand practitioners use for this state — it is not language that appears in the regulation itself. The sponsor may also proceed earlier if FDA affirmatively authorizes the study before day 30.

What is the IND submission process, step by step?

In order: (1) optionally, request a pre-IND meeting; (2) assemble the 312.23(a) content package; (3) submit via the FDA Electronic Submissions Gateway; (4) FDA issues written notice of the date of receipt, starting the 30-day clock; (5) FDA reviews for the clinical-hold grounds in 312.42(b) during that window; (6) absent a hold, the IND goes into effect automatically on day 30 and the sponsor may ship drug and begin dosing.

What happens if FDA places the IND on clinical hold?

No study subjects may be given the investigational drug (for a proposed study) or enrolled further (for an ongoing one) until FDA notifies the sponsor in writing that the hold is lifted. The review division must provide a written explanation of the hold’s basis within 30 days of imposing it. To resolve a hold, the sponsor submits a written request plus a complete response to FDA’s stated deficiencies; FDA then has 30 calendar days to respond in writing, either lifting or maintaining the hold.

Does the 30-day clock apply to every submission under an IND, or just the original filing?

The 312.40(b) 30-day “goes into effect” clock applies specifically to the original IND. Amendments, protocol changes, and annual reports are separate submission types under Part 312 with their own procedural rules (an amended or new protocol, for instance, generally does not itself require a fresh 30-day wait before proceeding, subject to any applicable clinical-hold action). Every submission still gets a Form FDA 1571 and its own sequential serial number.

Is a pre-IND meeting required before filing?

No. Nothing in 21 CFR Part 312 requires it. Most sponsors request one anyway for a novel product or where the nonclinical/CMC package involves real judgment calls, specifically to reduce the risk of a clinical hold once the IND is actually filed. See CASRAI’s Pre-IND Meeting guide for the full process.