513(g) Review Timelines & Typical FDA Outcomes

After submitting a 513(g) classification request, manufacturers commonly ask: how long will this take, and what will FDA's response actually tell me? The answers are more predictable than many manufacturers expect. FDA's performance on 513(g) reviews is tracked against MDUFA goals, and the structure of the response is relatively standardized.

513(g) Review Timeline: What to Expect

FDA's MDUFA V commitment for 513(g) requests is to provide a substantive response within 60 calendar days of receipt for 90% of submissions. This is a meaningful commitment — FDA tracks and reports performance against it quarterly. In practice, most 513(g) responses arrive within the 60-day window, and many arrive faster for straightforward classification questions.

The timeline from submission to response typically looks like this:

• Days 1–10: FDA receives and logs the submission, confirms fee payment, and sends an acknowledgment letter with a submission tracking number.
• Days 10–50: FDA assigns the submission to the appropriate CDRH device division. A reviewer with device-type expertise examines the device description, searches the product classification database for candidate product codes, and identifies the most appropriate regulatory class.
• Days 50–60: The response letter is drafted, reviewed internally, signed by the division director, and transmitted to the requester.

For genuinely novel devices where no close product code match exists, FDA may take slightly longer — the reviewer may need to consult with colleagues across divisions, or FDA may schedule a brief call or written exchange before finalizing the response. In these cases, FDA typically communicates the need for additional time before the 60-day target expires.

What a 513(g) Response Letter Contains

A typical 513(g) response letter is a structured document that addresses the device as described in the request. The response typically includes:

• Summary of the device description: FDA summarizes how it understood the device's intended use and design. This section is important to review carefully — if FDA's summary of your device differs from your intended description, the classification opinion may not accurately reflect your device's actual regulatory position.
• Product code identification: FDA identifies the three-letter product code (or codes) that most closely matches the device. The product code determines the applicable 21 CFR regulation section, regulatory class, and performance standards.
• Regulatory class: FDA states the regulatory class — Class I, II, or III — that applies to the device under the identified product code.
• Premarket submission requirement: FDA identifies the expected submission type: 510(k) (most common), De Novo, PMA, or exempt (no premarket submission required).
• Special controls and performance standards: If the device falls under a Class II product code with associated special controls, FDA may identify relevant guidance documents or performance standards that apply.

Typical Outcomes by Device Type

For Class I and Class II devices with clear predicates, 513(g) responses typically confirm a 510(k) pathway under an existing product code. These are the most straightforward outcomes, and the response often directly references cleared predicate devices in the FDA 510(k) database that serve as comparators.

For devices with novel features that place them outside existing product code categories, the 513(g) response may identify the nearest existing product code while noting that the novel features may require separate consideration — potentially via De Novo classification. In these cases, the response is still valuable even if it doesn't resolve every question, because it identifies the closest existing regulatory framework.

For devices that FDA cannot classify on the basis of the information provided — typically because the device description is too vague or the intended use is not fully defined — the response may decline to provide a specific classification opinion and recommend that the manufacturer clarify the device description or pursue a Pre-Submission meeting for more detailed discussion.

Acting on the 513(g) Response

Once you receive the 513(g) response, the first step is to verify that FDA's summary of the device description matches your actual device. If FDA's understanding of the intended use is narrower or broader than intended, the classification opinion may not be representative of the device as you plan to market it. In that case, consider whether a clarifying follow-up or a Pre-Sub meeting would be more appropriate than proceeding directly to a formal submission.

If the classification opinion is consistent with expectations, use the product code and class information to structure your premarket submission. For a 510(k), identify cleared devices under the same product code that can serve as predicates. For a De Novo, use the 513(g) response to frame the proposed classification regulation and special controls. For a PMA, begin scoping the clinical evidence requirements based on the class and regulation section identified.

Keep the 513(g) response in your regulatory file. Although it is not binding, it is a formal FDA document that can be referenced during subsequent submissions to demonstrate alignment with FDA's classification position. Reviewers who later encounter a 510(k) or De Novo for the same device will often find that a prior 513(g) response on file reduces the need for classification-related questions during the substantive review.

Frequently Asked Questions

How long does FDA take to respond to a 513(g) request?

FDA's MDUFA performance goal is to provide a substantive response to 90% of 513(g) requests within 60 calendar days of receipt. The clock starts when FDA receives the submission and confirms fee payment. FDA first sends an acknowledgment letter (typically within 5–10 business days), then a substantive response letter within the 60-day target. Most 513(g) responses arrive within the MDUFA target window, though complex or novel device classifications may require additional review time.

What does a typical 513(g) response letter contain?

A typical 513(g) response letter identifies: (1) the applicable product code for the device as described; (2) the device's regulatory class (Class I, II, or III); (3) the applicable CFR regulation section; (4) the expected premarket submission type (exempt, 510(k), De Novo, or PMA); and (5) any relevant performance standards or special controls associated with the product code. The letter is signed by the relevant CDRH division director and constitutes FDA's informal classification opinion. It is not a clearance, approval, or final order.

What if FDA's 513(g) response identifies a higher class than expected?

If the 513(g) response identifies Class III (PMA) when the manufacturer expected Class II (510(k)), several options are available. First, review whether the intended use as described was the most conservative scope — a narrower intended use may correspond to a lower classification. Second, consider requesting a Pre-Submission (Q-Sub) meeting to discuss the classification rationale with FDA and explore whether a De Novo pathway is viable. Third, review the applicable 21 CFR section and any CDRH guidance documents associated with the product code to understand the basis for the classification.

Can FDA refuse to answer a 513(g) request?

FDA may decline to provide a classification opinion in a 513(g) response if: (1) the device description is too vague to support a classification determination; (2) the device is not yet sufficiently developed to assess its intended use; or (3) the classification question is outside the scope of the 513(g) program. In these cases, FDA typically explains why a classification opinion cannot be provided and may suggest alternative mechanisms — such as a Pre-Sub meeting or a more fully developed submission — that would allow FDA to provide useful feedback.