The conventional wisdom is that a 510(k) is faster and cheaper than a De Novo request. FDA's review goal for a 510(k) is 90 FDA days and for a De Novo request 150 review days, and the De Novo user fee is several times higher. So founders often default to a 510(k), even when a device is genuinely novel and has no good predicate. If FDA then finds the device not substantially equivalent, the company can end up submitting a De Novo request anyway, after spending the time and money on a 510(k) that didn't work.
This article covers when a De Novo request is the better fit, what it does and doesn't give a company, and how to read the choice in diligence.
The Numbers: 510(k) vs De Novo
User fees: For fiscal year 2027 (October 1, 2026 through September 30, 2027), FDA's standard De Novo fee is $191,020 and the 510(k) fee is $28,653; qualifying small businesses pay 25% of each. Review goals are counted in FDA days: when FDA sends a request for additional information, the submission goes on hold, and the sponsor has 180 calendar days to send a complete response before the submission is considered withdrawn.
Beyond user fees: Regulatory consulting, testing and any clinical work add to the cost of either pathway, and a De Novo request generally needs more supporting evidence because there is no predicate to lean on.
The forced-conversion scenario: A company submits a 510(k) with a weak predicate, FDA finds the device not substantially equivalent, and the company then submits a De Novo request. It has paid two user fees, spent the 510(k) review time, and still has the De Novo review ahead of it.
When a 510(k) Fits
The 510(k) pathway fits when:
- A suitable predicate exists: a legally marketed device with the same intended use
- The device is substantially equivalent: the same technological characteristics, or different ones that don't raise different questions of safety and effectiveness
- FDA is likely to accept the predicate: ideally confirmed through a Pre-Submission, or consistent with published guidance
- The needed data are within reach: performance testing, and clinical data if the differences call for it
When these conditions are uncertain, the risk of a not-substantially-equivalent decision rises.
When a De Novo Request Fits
A De Novo request fits when:
- The device is novel and no legally marketed predicate exists, and its risk is low to moderate, so general controls, or general and special controls, can provide reasonable assurance of safety and effectiveness
- The company has the data to show safety and effectiveness without a predicate comparison
- A 150-day review goal is acceptable in exchange for a better-matched pathway
A De Novo request can be submitted directly, when the requester determines there is no legally marketed predicate, or after FDA finds a device not substantially equivalent in a 510(k). FDA either grants or declines it; a declined device remains in class III.
What a De Novo Does and Doesn't Give a Company
A granted De Novo creates a new classification for that type of device, with the classification and any special controls written around the first device. FDA notes that devices classified through De Novo may be used as predicates for future 510(k) submissions. That cuts both ways: later competitors with similar devices may be able to use the 510(k) pathway, citing the De Novo device as their predicate. Being first defines the classification; it doesn't keep competitors out.
A Public Example
On September 21, 2021, FDA granted a De Novo request (DEN200080) for Paige Prostate, software that flags areas of a scanned prostate biopsy image suspicious for cancer so a pathologist can review them. The decision created a class II classification, "software algorithm device to assist users in digital pathology" (21 CFR 864.3750), with special controls. With no predicate for AI software of that kind, De Novo was the pathway, and the classification it created may be used by later devices of the same type.
Questions for Choosing, or Reading, the Pathway
- Can a single predicate be named with the same intended use, and is the technological comparison defensible?
- Has FDA weighed in through a Pre-Submission?
- Does the company have the data to support safety and effectiveness without a predicate?
- How could later competitors use the classification if a De Novo is granted?
- How much does the timeline matter compared with the risk of a not-substantially-equivalent decision?
Using a Pre-Submission
FDA's Pre-Submission process, part of the Q-Submission program, lets a company describe its device, proposed predicate, data plan and substantial equivalence argument before committing to a pathway. There is no FDA user fee for it, and FDA's written feedback can say whether the proposed pathway looks appropriate or whether a De Novo request looks more suitable.
Red Flag: A 510(k) Without a Real Predicate
A company says it will use a 510(k) because it is faster and cheaper, but its device is genuinely novel and the named predicate differs in technology. That raises the risk of a not-substantially-equivalent decision and a second submission, and it is worth asking whether FDA has weighed in.
The Bottom Line
A 510(k) is the faster path only when the predicate is solid and FDA agrees with the substantial equivalence argument. With a weak predicate, a not-substantially-equivalent decision followed by a De Novo request can take longer and cost more than a De Novo request from the start. For a genuinely novel device, De Novo is often the better-matched pathway, with the understanding that the classification it creates can later serve competitors too.
References
- FDA. "De Novo Classification Request." fda.gov
- FDA. "Premarket Notification 510(k)." fda.gov
- FDA. "510(k) Submission Process." fda.gov
- FDA. "The 510(k) Program: Evaluating Substantial Equivalence in Premarket Notifications [510(k)]." Final guidance, July 2014. fda.gov
- FDA. "How to Study and Market Your Device." fda.gov
- FDA. "Medical Device User Fee Amendments (MDUFA) Fees." fda.gov
- FDA. "Requests for Feedback and Meetings for Medical Device Submissions: The Q-Submission Program." Final guidance, May 2025. fda.gov
- FDA De Novo database. DEN200080, Paige Prostate (Paige.AI). Granted September 21, 2021; 21 CFR 864.3750, software algorithm device to assist users in digital pathology; product code QPN. accessdata.fda.gov
Need a Custom Analysis?
Vantage full reports assemble the public record on a company, cite factual claims to their sources, and are reviewed by Arvind Ravinutala, MD, and Aswini Ravinutala, BME. Start with a free 20-minute call.