Section 513 of the FD&C Act, added by the Medical Device Amendments of 28 May 1976, sets up FDA's three device classes (FDA). The class is not fixed for ever. On 6 October 2026, FDA published a notice exempting 14 product codes of class II clinical toxicology test systems from 510(k) (FDA).
Knowing a device's class is only the start. This article explains what each class actually requires, how exemptions work and how a class can change. For how to find the right regulation and product code, see our guide to the FDA device classification database. For a comparison with the EU, see classification of medical devices in the EU and US.
The three classes at a glance
| Class | FDA risk description | Controls | Usual route to market |
|---|---|---|---|
| I | Low to moderate risk | General controls | Mostly 510(k)-exempt |
| II | Moderate to high risk | General controls and special controls | 510(k), unless exempt |
| III | High risk | General controls and premarket approval | PMA |
Source: FDA, Regulatory Controls.
Each class adds controls on top of the one below. A Class III device is still subject to every general control.
General controls: what every device carries
According to FDA, general controls apply to all devices unless a regulation exempts them. They come from these sections of the FD&C Act:
| FD&C Act section | Covers |
|---|---|
| 501 | Adulterated devices |
| 502 | Misbranded devices, including false or misleading labelling |
| 510 | Establishment registration, device listing and premarket notification (510(k)) |
| 516 | Banned devices |
| 518 | Notification, repair, replacement, refund and mandatory recall |
| 519 | Records and reports, including adverse event reports, device tracking, UDI and reports of corrections and removals |
| 520 | General provisions, including restricted devices, good manufacturing practice and investigational device exemptions |
Source: FDA, Regulatory Controls and General Controls for Medical Devices.
In practice, for a manufacturer this means registration and listing, labelling that is not false or misleading, a quality system under 21 CFR Part 820, adverse event reporting and UDI. Our article on FDA device listing covers the listing step.
If a device type is exempt from any general control, the exemption is written in its classification regulation. FDA's example is the manual toothbrush in 21 CFR 872.6855.
Special controls: what Class II adds
FDA places a device in Class II when general controls alone are not enough, but there is enough information to set special controls. According to FDA, special controls are usually device-specific and include:
performance standards;
postmarket surveillance;
patient registries;
special labelling requirements;
premarket data requirements;
guidelines.
The special controls are written into the classification regulation. In our view, they are the most useful part of the regulation for a Class II manufacturer, because they tell you what the 510(k) and the technical file must show.
A worked example: radiological CADe/CADx software
21 CFR 892.2090 covers radiological computer-assisted detection and diagnosis software: software that aids in detecting, localising and characterising findings on medical images, to inform decisions made by the clinical user. It is Class II (special controls). The special controls include:
Design verification and validation:
a detailed description of the image analysis algorithm, its inputs, outputs and limitations;
pre-specified performance testing protocols and datasets;
standalone performance results, using measures such as sensitivity, specificity and ROC analysis, on a test dataset representative of the intended patient population;
results showing improved assisted-read performance by the intended users;
software documentation, including hazard analysis, requirements and design specifications, traceability, test results and cybersecurity measures.
Labelling:
the patient population, intended user and reading protocol;
device inputs and outputs, and compatible imaging hardware and protocols;
warnings on situations in which the device may fail or underperform;
a summary of the performance testing, including sub-analyses by relevant confounders.
Hypothetical example: a company developing fracture-detection software that fits this regulation can map each special control to a record in its design history file before writing the 510(k). In our view, this is the most efficient way to use the regulation: the special controls become a checklist for both the submission and the file, so nothing is written twice. Whether a specific product fits the regulation depends on its intended use and indications for use.
For software classification in more detail, see our article on medical device classifications for software and AI.
PMA: what Class III adds
Class III devices need premarket approval under section 515, unless a narrower route applies. FDA places a device in Class III when it supports or sustains life, is of substantial importance in preventing impairment of health, or presents a potential unreasonable risk of illness or injury, and general and special controls are not enough. Our article on Class 3 medical devices covers PMA, the Class III 510(k) and the humanitarian device exemption.
510(k) exemptions
According to FDA, most Class I devices and some Class II devices are exempt from 510(k). The exemption has limits:
it applies only to devices with the existing or reasonably foreseeable characteristics of commercially distributed devices of that type;
the general limitations are in the ".9" section of each part (21 CFR 862.9 to 892.9). If a device meets any of those conditions, a 510(k) is still required;
FDA may limit the exemption to specific devices within a regulation.
Exemption from 510(k) does not exempt a device from the quality system. According to FDA, all devices are subject to the Quality Management System Regulation unless 21 CFR 820 provides an exception or exemption.
Section 3054 of the 21st Century Cures Act requires FDA to publish in the Federal Register the Class I and Class II device types that no longer need a 510(k). Recent notices:
| Date | Notice | Devices | Product codes |
|---|---|---|---|
| 6 October 2026 | 91 FR 63478 | Class II clinical toxicology test systems | 14 |
| 18 June 2025 | 90 FR 25889 | Class II clinical electronic thermometers | 1 |
| 22 July 2020 | 85 FR 44186 | Several Class II device types | 5 |
Source: FDA, Class I and Class II Device Exemptions.
How a class changes
FDA reclassifies device types, not individual devices (FDA). There are three main routes.
| Route | Applies to | How it works |
|---|---|---|
| Section 513(e) | Already classified device types, except automatic Class III under 513(f)(1) | FDA acts on its own or on a petition, based on new information. It publishes a proposed order, convenes a device classification panel and considers public comments before a final order |
| Section 513(f)(3) | Postamendments devices automatically in Class III | FDA acts on its own or on a petition to move the type to Class I or II. It may refer the petition to a classification panel |
| De Novo, section 513(f)(2) | A new device with no predicate | Classifies the device into Class I or II and creates a new classification regulation |
Source: FDA, Reclassification.
A postamendments device is one not in commercial distribution before 28 May 1976. It is automatically Class III under section 513(f)(1) and needs a PMA unless it is classified through De Novo, reclassified, or found substantially equivalent to a predicate that does not require a PMA. Our article on De Novo review covers that route.
In our view, manufacturers should check the Federal Register for their product codes at least once a year. A new exemption can remove a 510(k), and a reclassification can add special controls that a modified device must then meet.
Conclusion
The class tells you which layer of control applies. General controls apply to every device. Class II adds device-specific special controls written into the regulation. Class III adds premarket approval. Exemptions and reclassification can change the picture, but only for a whole device type and only through published FDA action.
In our view, the classification regulation is the most practical document in the US file. Read its identification, its class, its special controls and its exemption limits, and map each one to a record.
If you need help working out what your device's class means for your submission and technical file, our regulatory strategy team can help, or contact MedQAIR.
Frequently asked questions
Who decides a device's class in the US?
FDA, through the classification regulations in 21 CFR Parts 862 to 892, under section 513 of the FD&C Act. New device types are classified through De Novo or remain Class III.
Are all Class I devices exempt from 510(k)?
No. Most are, but the exemption is subject to the limitations in 21 CFR 862.9 to 892.9 and to the wording of each regulation.
Do general controls apply to exempt devices?
Yes. A 510(k) exemption only removes the premarket notification. Registration and listing, labelling, the quality system and the other general controls still apply unless the regulation says otherwise.
What are special controls?
Device-specific requirements for Class II devices, such as performance standards, labelling requirements, premarket data requirements and postmarket surveillance. They are written into the classification regulation.
Can a device's class change?
Yes, but for a whole device type. FDA can reclassify under sections 513(e) or 513(f)(3), and a De Novo grant classifies a new device type into Class I or II.
