The clock starts the moment the inspector hands you the Form 483. You have 15 business days, and the FDA finally wrote down what it wants to see in that window.
In March 2026 the agency published its first standalone draft guidance on responding to 483 observations from a drug CGMP inspection. Before this, response practice was industry convention. Now there’s a documented expectation, and the FDA reviews your response before deciding whether to escalate to a warning letter.
What the guidance asks for, per observation: a patient- and product-focused risk assessment covering both inventory and distributed drugs, a detailed investigation report with scope, root cause, and affected lot numbers, and a corrective and preventive action plan with real completion dates. Acknowledging the problem isn’t enough. The agency wants to see you’ve mapped the risk and committed to fixed timelines.
If you can’t fix everything in 15 business days, the FDA’s own recommendation is to submit a CAPA plan with timelines and interim measures rather than going quiet. Silence reads as non-engagement, and non-engagement is what moves a file toward enforcement.
The strategic point most quality teams miss: the 483 response is the last cheap off-ramp. A warning letter is public, it cites violated regulations, and it follows you into every future inspection and investor call. The 15-day response is private and still under your control. Compliance platforms like Regfo are built around that window precisely because it’s where the outcome gets set.
The FDA recommends 15 business days. It rarely extends them.