What an FDA US Agent Actually Does — and What Happens When Yours Doesn't Respond

The Role Most Foreign Device Manufacturers Underestimate

If your medical device company is headquartered outside the United States and you distribute devices in the US market, you are legally required to designate a US Agent. This is not a formality. It is not a mailing address service. Under 21 CFR Part 807.40, your US Agent is the FDA's primary point of contact for everything related to your device — and if that person or entity fails to respond, the downstream consequences can be severe enough to remove your device from the market entirely.

Yet time and again, foreign manufacturers treat US Agent designation as a checkbox, assigning the role to a distant contact or a low-cost service provider with no actual regulatory expertise. This post breaks down what a US Agent is legally obligated to do, what happens when that obligation goes unmet, and how to evaluate whether yours is actually protecting your regulatory standing.

What the Regulations Actually Require

The statutory basis for the US Agent requirement is Section 510(f) of the Federal Food, Drug, and Cosmetic Act (FD&C Act), implemented through 21 CFR 807.40. The regulation requires that every foreign establishment that is required to register with the FDA designate a US Agent who:

• Resides or maintains a place of business in the United States
• Assists the FDA in communications with the foreign establishment
• Is available to FDA during normal business hours
• Is the FDA's primary contact for emergencies, inspections, and regulatory correspondence

The FDA's guidance document 'Registration and Listing of Medical Device Establishments' reinforces that the US Agent must be reachable and must facilitate actual communication — not simply receive mail. Critically, if FDA cannot reach your US Agent, it is treated as the equivalent of being unable to reach you. That distinction matters enormously when the agency is trying to resolve a safety issue, a field correction, or a recall classification.

What a Competent US Agent Actually Does Day-to-Day

A qualified US Agent is not passive. They are an active regulatory liaison. Their responsibilities include:

• Facilitating FDA establishment inspections: Under 21 CFR 820 (Quality System Regulation, transitioning to 21 CFR Part 820 aligned with ISO 13485 under the Quality Management System Regulation), your US Agent coordinates logistics and communications when FDA inspectors intend to inspect your facility — even if that facility is overseas.
• Receiving and forwarding official FDA correspondence: This includes warning letters, untitled letters, 483 observations, and recall notices. These documents require timely responses — often within 15 business days — and missing that window because your agent did not forward the communication is not a defense FDA will accept.
• Supporting registration and listing accuracy: Annual registration renewal through the FDA Unified Registration and Listing System (FURLS) is required, and your US Agent is expected to verify that establishment and device listing information is current and accurate.
• Serving as a conduit during adverse event reporting reviews: If FDA has questions related to a Medical Device Report (MDR) filed under 21 CFR Part 803, your US Agent may be the first point of contact.

What Happens When Your US Agent Goes Dark

This is where companies learn hard lessons. If FDA attempts to contact your US Agent and receives no response, the agency has authority under Section 301(e) of the FD&C Act to pursue enforcement action for failure to permit access or failure to make required reports. Practically speaking, here is what can happen:

• Your establishment registration can be flagged or placed on import alert. FDA's Import Alert system — including Import Alert 89-08 for unregistered or non-compliant device establishments — can result in your devices being detained at US ports of entry without physical examination.
• You may be listed as a non-compliant manufacturer in FDA's publicly accessible registration database, signaling risk to US distributors, hospital procurement departments, and partners conducting supplier qualification audits.
• FDA may initiate a directed inspection or refer the matter to the Office of Criminal Investigations (OCI) in cases involving significant public health concern.
• Your 510(k) clearances or PMA approvals can be put at risk. If FDA determines that correspondence related to a cleared or approved device went unacknowledged, it creates grounds for mandatory recall or market withdrawal proceedings.

The reputational and commercial damage from an import alert alone can take 12 to 24 months to remediate — if it can be remediated at all.

How to Evaluate Your Current US Agent

Ask yourself these questions about your current US Agent:

• Do they have documented regulatory affairs expertise, or are they simply a registered address provider?
• Have they ever communicated proactively with you about a regulatory development — or only when you contacted them first?
• Do they understand the device classification, applicable standards, and current FDA enforcement priorities for your product category?
• Can they draft or review a response to an FDA inquiry, or would you have to engage outside counsel at the last minute?

If the honest answers to these questions give you pause, that is important information. The cost of replacing an underperforming US Agent is trivial compared to the cost of an import alert or a delayed market entry caused by missed FDA correspondence.

The Standard Your US Agent Should Be Held To

A US Agent with real value is one who functions as an embedded regulatory intelligence resource for your company. They should be conversant in the FDA's current enforcement priorities as outlined in the Center for Devices and Radiological Health (CDRH) annual guidance agendas. They should understand how product changes trigger new 510(k) obligations under 21 CFR 807.81(a)(3) and the associated FDA guidance on Deciding When to Submit a 510(k) for a Change to an Existing Device. They should be able to escalate internal alerts within your organization when FDA communications require action — not simply forward an email and wait.

For manufacturers navigating the transition to the updated Quality Management System Regulation (QMSR) under 21 CFR Part 820, which aligns more closely with ISO 13485:2016 and took effect in February 2026, having a US Agent who understands the implications for your technical documentation and quality system records is no longer optional — it is a baseline expectation.

ADB Consulting and CRO Inc. Serves as US Agent for Foreign Device Manufacturers

At ADB Consulting and CRO Inc., we serve as US Agent for medical device manufacturers who need more than a compliance checkbox. Andre Butler and the ADB team bring deep CDRH experience across 510(k), De Novo, and PMA pathways, and we treat every US Agent engagement as an active regulatory partnership — not a passive service contract. We monitor your regulatory standing, respond to FDA in real time, and keep your leadership informed before small issues become enforcement actions.

If you are unsure whether your current US Agent would catch a warning letter before it escalated, that uncertainty is worth resolving today.

Book a free discovery call with ADB Consulting and CRO Inc. at adbccro.com. We will review your current US Agent arrangement, identify any gaps in your regulatory coverage, and tell you plainly what you need to protect your device's standing in the US market.

Related reading: our US Agent service covers this in more depth.