EU IVDR Classification Rules: The Complete Guide to IVD Risk Classes A–D

Why IVDR Classification Is the Most Important Decision You Will Make

Under the EU In Vitro Diagnostic Regulation (IVDR) 2017/746, classification determines almost everything about your regulatory pathway: whether you need a Notified Body, how deep your performance evaluation must go, what post-market surveillance obligations apply, and how long your conformity assessment will take. Get it wrong and you face CE mark rejection, costly delays, or even market withdrawal. Get it right and you have a clear, defensible path to market.

The shift from the old In Vitro Diagnostic Directive (IVDD) to the IVDR fundamentally changed how IVDs are classified. Under the IVDD, roughly 80% of IVDs were self-certified — no Notified Body required. Under the IVDR, that figure has flipped: approximately 78% of IVDs now require Notified Body involvement. The classification rules are the mechanism that drives this change.

This guide walks through every classification rule in Annex VIII of the IVDR, explains the implementing rules that govern how they are applied, provides real device examples for each class, addresses software classification, and covers the transitional timelines and the EU Commission's December 2025 simplification proposal that may change certain classifications going forward.

The IVDD vs IVDR Classification Shift

How Classification Worked Under the IVDD

The IVDD used a list-based system. IVDs were categorized into:

• Annex II, List A: Highest-risk devices, such as those for detecting HIV, Hepatitis B, and Hepatitis C. Required Notified Body review.
• Annex II, List B: Moderate-risk devices, such as blood glucose monitoring tests and rubella tests. Required Notified Body review.
• Self-testing devices: Devices intended for home use, such as pregnancy tests.
• Everything else: The vast majority of IVDs were self-declared by the manufacturer with no external oversight.

This system had a fundamental problem: it was not risk-based. A device's classification depended on whether it appeared on a specific list, not on an assessment of the risk it posed to patients or public health. Many clinically significant IVDs fell outside the lists and were self-certified with minimal regulatory scrutiny.

How the IVDR Changed Everything

The IVDR replaced the list-based system with a rules-based, four-tier classification system aligned with the risk-based approach used for medical devices under the EU MDR. IVDs are now classified into Classes A, B, C, and D based on:

• Individual patient risk: The potential harm to the patient from an incorrect result
• Public health risk: The potential for widespread impact if a device produces incorrect results
• Intended purpose: What the device is designed to detect or measure
• User type: Whether the device is used by professionals or laypersons

The result: a classification system that is more granular, more defensible, and significantly more demanding for most manufacturers.

The Four IVDR Risk Classes

The IVDR establishes four risk classes in ascending order of risk. The classification determines the conformity assessment route, the depth of technical documentation, and the level of Notified Body involvement.

Class A — Low Risk

Attribute	Detail
Individual risk	Low
Public health risk	Low
Notified Body involvement	No (self-declared), unless sterile
Conformity assessment	Self-declaration of conformity

Examples: Specimen receptacles (collection tubes), buffer solutions, diluents, wash buffers, general laboratory instruments (e.g., centrifuges, pipettes), instruments for general laboratory use that do not have a specific IVD intended purpose.

Class A devices are the only IVDs that can still be self-certified under the IVDR (unless they are supplied sterile, in which case a Notified Body is required). These are products used in the laboratory that do not produce a diagnostic result themselves and pose minimal risk even if they fail.

Class B — Moderate Risk

Attribute	Detail
Individual risk	Moderate
Public health risk	Low
Notified Body involvement	Yes
Conformity assessment	Full quality management system + technical documentation assessment

Examples: Clinical chemistry analyzers and reagents, pregnancy self-test kits, fertility tests, cholesterol self-test kits, rapid test devices for influenza (non-pandemic), vitamin D assays.

Class B is the default classification for IVDs that do not fall under the more specific rules for Class C or Class D. Many devices that were self-certified under the IVDD now fall into Class B and require Notified Body certification for the first time.

Class C — High Risk

Attribute	Detail
Individual risk	High
Public health risk	Moderate
Notified Body involvement	Yes
Conformity assessment	Technical documentation review + performance evaluation review + QMS audit

Examples: Companion diagnostics, genetic tests, cancer screening tests (e.g., HPV, BRCA), infectious disease tests for agents with moderate transmission risk, HLA typing for transplantation (non-critical markers), PSA tests, blood glucose monitoring reagents, devices for detecting infectious agents where false results could lead to life-threatening mismanagement.

Class C captures a broad range of IVDs where incorrect results could directly affect clinical decisions for individual patients. This is the largest class of devices requiring Notified Body involvement. Companion diagnostics, which link a specific drug therapy to a diagnostic test, are specifically captured under Rule 3 as Class C.

Class D — Highest Risk

Attribute	Detail
Individual risk	High
Public health risk	High
Notified Body involvement	Yes (with additional scrutiny)
Conformity assessment	Full assessment + batch release verification by EU Reference Laboratory

Examples: HIV tests (detection/confirmation), Hepatitis B and C tests, blood grouping tests (ABO, Rh, Kell, Kidd, Duffy), tissue typing for transplant compatibility, tests for detecting life-threatening transmissible agents in blood/tissue/cell donations (e.g., HTLV, syphilis, malaria, Ebola, SARS-CoV-2 during pandemic classification).

Class D devices undergo the most stringent conformity assessment. In addition to the standard Notified Body review, Class D devices are subject to batch verification by EU Reference Laboratories (EURLs) and may undergo the scrutiny procedure, where an expert panel reviews the Notified Body's assessment before certification is granted.

The 7 Classification Rules: A Practical Walkthrough

Annex VIII of the IVDR contains 10 implementing rules and 7 classification rules. You must apply all 7 classification rules to every IVD — the rule that produces the highest classification wins. The implementing rules provide the framework for how to apply the classification rules.

Implementing Rules: How to Apply the Classification Framework

Before diving into the specific rules, the implementing rules in Annex VIII Chapter I, Section 1 establish critical principles:

1. Rule 1.1: Classification is governed by the device's intended purpose as defined by the manufacturer.
2. Rule 1.2: If a device is used in combination with another device, each device is classified separately. An ELISA reader and its reagent kit, sold independently, are classified separately.
3. Rule 1.3: Accessories are classified in their own right, separately from the device they support.
4. Rule 1.4: Software that drives or influences a device falls in the same class as the device. Standalone IVD software is classified independently based on its own intended purpose.
5. Rule 1.5: Calibrators are classified in the same class as the device they calibrate.
6. Rule 1.6: Control materials are classified in the same class as the device they support.
7. Rule 1.7: The manufacturer must consider all classification and implementation rules.
8. Rule 1.8: If a device has multiple intended purposes falling into different classes, the highest class applies.
9. Rule 1.9: If several classification rules apply to the same device, the rule resulting in the higher classification applies.

Classification Rule 1 — Life-Threatening Transmissible Agents

Devices intended to be used for detecting transmissible agents in blood, tissues, cells, or organs to assess donor suitability; devices used to detect life-threatening diseases with high transmissibility; and devices used to determine infectious load where critical for patient management.

Classification: Class D

This is the highest-risk rule. It captures devices that screen the blood and tissue supply and devices that detect diseases that can spread rapidly through populations. The rationale is clear: an incorrect result for these devices could endanger not just individual patients but entire populations.

Specific examples covered by Rule 1:

• HIV detection/confirmation tests
• Hepatitis B virus (HBV) detection
• Hepatitis C virus (HCV) detection
• HTLV detection
• Ebola and other hemorrhagic fever virus detection
• Syphilis screening for blood donation
• Malaria screening for blood donation
• SARS-CoV-2 detection (classified as Class D per MDCG 2020-16)

Note on SARS-CoV-2: Team-NB (the European Association of Notified Bodies) has issued a position paper recommending reclassification of SARS-CoV-2 tests from Class D to Class C, reflecting reduced pandemic-era risk. As of early 2026, these tests remain Class D per MDCG guidance, but this may change.

Classification Rule 2 — Blood Grouping and Tissue Typing

Devices intended for blood grouping or tissue typing to ensure immunological compatibility of blood, blood components, cells, tissue, or organs for transfusion, transplantation, or cell administration.

Classification: Class C by default, Class D when testing for specific markers

The following markers trigger Class D under Rule 2:

• ABO system [A (ABO1), B (ABO2), AB (ABO3)]
• Rhesus system [RH1 (D), RHW1, RH2 (C), RH3 (E), RH4 (c), RH5 (e)]
• Kell system [Kel1 (K)]
• Kidd system [JK1 (Jka), JK2 (Jkb)]
• Duffy system [FY1 (Fya), FY2 (Fyb)]

All other blood grouping and tissue typing tests default to Class C.

The rationale: a mismatch in ABO or Rh typing during transfusion can cause acute hemolytic reactions and death. The risk is both individual (patient death) and systemic (blood supply integrity).

Classification Rule 3 — High Individual Risk Devices

Rule 3 is the broadest and most complex classification rule. It captures IVDs where incorrect results could lead to serious harm to individual patients. The rule has multiple sub-clauses (a through l):

Sub-clause	Description	Class
(a)	Detecting sexually transmitted agents (e.g., Chlamydia, Gonorrhea)	C
(b)	Detecting agents in cerebrospinal fluid or blood (not covered by Rule 1)	C
(c)	Detecting infectious agents with a high risk of propagation if misdiagnosed	C
(d)	Detecting infectious agents in pregnant women where the agent could harm the fetus	C
(e)	Detecting infectious agents where fatal outcomes are likely if not treated	C
(f)	Detecting infectious agents with a risk of high suspected transmission	C
(g)	Pre-natal screening for maternal immune status (e.g., rubella, toxoplasmosis)	C
(h)	Screening for selection of patients for selective therapy (e.g., cancer)	C
(i)	Monitoring levels of medicines, substances, or biological components where decisions could impact patient health	C
(j)	Managing patients with life-threatening diseases or conditions	C
(k)	Companion diagnostics	C
(l)	Detecting the presence of or exposure to a transmissible agent, if results inform treatment	C

Key examples:

• HPV DNA tests for cervical cancer screening — Class C (Rule 3h)
• BRCA genetic tests — Class C (Rule 3h)
• HbA1c monitoring tests for diabetes — Class C (Rule 3i)
• Therapeutic drug monitoring (e.g., immunosuppressant levels) — Class C (Rule 3i)
• Companion diagnostics for targeted cancer therapies — Class C (Rule 3k)
• Rubella immunity screening during pregnancy — Class C (Rule 3g)
• Lyme disease detection — Class C (Rule 3l)
• PSA screening tests — Class C (Rule 3h)

Classification Rule 4 — Self-Testing Devices

Devices intended for self-testing.

Classification: Class C by default, Class B for specific device types

Self-testing devices (those used by laypersons at home) are generally classified as Class C due to the risk that users may misinterpret results without professional guidance. However, the IVDR allows the Commission to classify certain self-testing devices as Class B through implementing acts.

Devices currently classified as Class B for self-testing include:

• Pregnancy self-tests
• Fertility self-tests
• Cholesterol self-tests
• Urine dipstick tests for general health monitoring
• Glucose self-monitoring tests

Classification Rule 5 — General Laboratory Use

(a) Products for general laboratory use, not intended by the manufacturer for specific IVD use. (b) Instruments intended by the manufacturer for specific IVD use.

Classification: Class A

Rule 5 covers the infrastructure of laboratory diagnostics — instruments, generic reagents, and consumables that support testing but do not themselves generate diagnostic results.

Examples:

• PCR thermocyclers — Class A (Rule 5b)
• Centrifuges — Class A (Rule 5a)
• ELISA plate readers — Class A (Rule 5b)
• Generic buffer solutions — Class A (Rule 5a)
• Wash solutions and diluents — Class A (Rule 5a)
• Nucleic acid extraction kits without specific analyte claims — Class A (Rule 5a)

Important caveat: Software that drives a Class A instrument is also Class A (per implementing rule 1.4). However, if the same software independently interprets results or makes diagnostic claims, it may be classified higher based on its own intended purpose.

Classification Rule 6 — Control Materials and Calibrators

Control materials with quantitative or qualitative assigned values, and calibrators.

Classification: Class B by default; same class as the device they support if higher

Control materials and calibrators are assigned to the same class as the device for which they are intended (implementing rules 1.5 and 1.6). However, if no specific device is identified, they default to Class B.

Classification Rule 7 — Specimen Receptacles

Devices intended for specimen collection and storage.

Classification: Class A

Specimen receptacles include collection tubes, urine cups, swabs, and other containers used to collect and transport patient samples. These are Class A unless they have features that trigger higher classification (e.g., if they contain specific preservatives or reagents linked to a higher-class device).

Classification Decision Flowchart

When classifying your IVD, follow this process:

1. Define the intended purpose precisely. Include the analyte, specimen type, clinical indication, and user (professional vs. layperson).
2. Apply all 7 classification rules from Annex VIII, starting with Rule 1.
3. For each applicable rule, determine the class and document the rationale.
4. Apply implementing rules 1.8 and 1.9 — if multiple rules apply, use the highest classification.
5. Document the classification rationale in your technical documentation, citing the specific rule numbers and sub-clauses.

The waterfall approach: Walk through Annex VIII from Rule 1 to Rule 7. Stop at the first rule that matches your device's intended purpose. Then verify no higher rule also applies. The result is your classification.

Software Classification Under IVDR

Software classification is one of the most frequently asked-about topics in IVDR compliance. The rules are clear but require careful application.

Software That Drives or Influences a Device (Implementing Rule 1.4)

If software drives a device or influences its use, it falls in the same class as the device. Examples:

• Software that operates a CRP analyzer — Class A (same as the analyzer)
• Software that controls an ELISA plate reader — Class A (same as the reader)
• Software that automates a PCR thermocycler — Class A (same as the thermocycler)

Standalone IVD Software (SaMD)

If software is independent of any device and provides diagnostic information on its own, it is classified based on its own intended purpose:

• Software that interprets HIV immunoassay results — Class D (Rule 1)
• Software that classifies Pap smears as normal/abnormal — Class C (Rule 3h)
• Software that calculates HbA1c values for diabetes monitoring — Class C (Rule 3i)
• Software that performs high-resolution HLA analysis for transplantation — Class C (Rule 2)

Embedded vs Standalone

Software embedded within a hardware device undergoes the same conformity assessment as the whole device. Standalone software (SaMD) undergoes its own conformity assessment based on its independent classification.

Companion Diagnostics: A Special Case

Companion diagnostics (CDx) are IVDs that are essential for the safe and effective use of a corresponding medicinal product. Under the IVDR:

• CDx are classified as Class C under Rule 3(k)
• They require Notified Body assessment plus review of the drug-test linkage by a medicinal product authority (EMA or national authority)
• The conformity assessment for CDx is among the most demanding in the IVDR framework
• If a CDx also meets criteria for Rules 1 or 2 (e.g., it detects an infectious agent), it would be classified as Class D instead

The FDA vs EU pathway divergence for CDx is notable. In the US, the FDA has begun reclassifying many high-risk IVDs (including CDx) from Class III (requiring PMA) to Class II (enabling 510(k) pathway). In the EU, CDx remain firmly in Class C with full Notified Body assessment required.

Conformity Assessment by Class

Your classification directly determines the conformity assessment route:

Class	Self-Certification	Notified Body QMS Audit	Technical Documentation Review	Performance Evaluation Review	EURL Batch Verification
A	Yes (unless sterile)	No	No	No	No
B	No	Yes	Yes	Yes	No
C	No	Yes	Yes	Yes	No
D	No	Yes	Yes	Yes	Yes

For Class D devices, EU Reference Laboratories (EURLs) perform batch verification and may conduct performance testing on representative samples. This adds time and complexity to the conformity assessment process.

Transition Timelines: Where We Stand in 2026

The IVDR transition has been extended multiple times due to Notified Body capacity constraints. As of April 2026, the current transition timelines under Regulation (EU) 2023/607 are:

Class	Transition Deadline	Conditions
Class D	December 31, 2027	Must have applied to a Notified Body by May 26, 2025
Class C	December 31, 2028	Must have applied to a Notified Body by May 26, 2026
Class B and Class A sterile	December 31, 2029	Must have applied to a Notified Body by May 26, 2027

As of late 2025, there are 19 Notified Bodies designated under the IVDR — a significant increase from the initial capacity bottleneck, but still raising questions about whether capacity is sufficient for the volume of Class C and B devices transitioning.

The December 2025 EU Simplification Proposal

On December 16, 2025, the European Commission published Proposal 2025/0404 (COD) — a 170-page proposal to amend both the MDR and IVDR. While this proposal covers many areas, several provisions directly affect IVD classification:

Targeted Classification Changes

• Software reclassification: The proposal introduces revised classification rules for software, potentially moving certain standalone IVD software into lower risk classes
• Reusable device provisions: Adjustments for certain device categories that may warrant reclassification
• Streamlined conformity assessment: Reduced re-certification obligations for lower-risk devices
• Remote audits: Greater acceptance of remote audit methods for Class B and C devices

Timeline

The proposal is currently before the European Parliament and Council. It is expected to be adopted and become applicable by Q2 2027. Changes to classification rules would apply 6 months after entry into force for most provisions.

What This Means for Manufacturers

• Continue classifying devices under the current IVDR rules
• Monitor the legislative process for the simplification proposal
• Begin strategic planning for potential reclassification of software-based IVDs
• Document classification rationale thoroughly — a well-documented classification will make any future transition easier

MDCG Guidance Documents

The Medical Device Coordination Group (MDCG) has published guidance to support classification decisions:

• MDCG 2020-16 rev.3 (updated July 2024): Guidance on classification rules for IVDs — includes flowcharts, examples, and a specific flowchart for companion diagnostic determination
• MDCG 2021-24: Guidance on classification of medical devices (MDR, but provides useful context)

These guidance documents are not legally binding but are considered best practice. Notified Bodies expect manufacturers to have considered them when justifying classification decisions.

Near-Patient Testing Classification

Near-patient testing (NPT) — also called point-of-care testing (POCT) — is IVD testing performed outside a traditional laboratory, typically at the site of patient care. Under the IVDR, near-patient testing has specific classification implications:

• A device intended for near-patient testing is classified based on the same classification rules as its laboratory equivalent, but the conformity assessment requirements are enhanced
• Near-patient testing devices must meet the requirements of Annex IX, Chapter II, Section 5.1 in addition to the standard conformity assessment — this includes specific evaluation of usability and instructions for use in the hands of non-laboratory personnel
• The IVDR draws a distinction between self-testing (layperson use) and near-patient testing (healthcare professional use outside the lab), and the requirements differ accordingly

This is an area where many manufacturers are caught off-guard: a Class B laboratory test that works perfectly in the hands of trained lab technicians may require additional conformity assessment steps when the same test is marketed for near-patient use in a clinic or emergency department.

Laboratory-Developed Tests (LDTs / In-House IVDs)

The IVDR includes provisions for in-house IVDs (also called laboratory-developed tests or LDTs) manufactured and used within health institutions. These are exempt from certain IVDR requirements, provided that:

• The laboratory has a quality management system in place
• The device is not transferred to another legal entity
• The target patient group's needs cannot be met by an equivalent CE-marked IVD
• The health institution justifies why the in-house device is necessary
• The device complies with the general safety and performance requirements

While LDTs are exempt from classification under the IVDR, they remain a contentious regulatory area. The EU Commission's December 2025 simplification proposal includes expanded flexibility for in-house devices, recognizing that the current IVDR provisions may be too restrictive for laboratories developing tests for rare conditions or emerging diseases.

Common Classification Mistakes

1. Only applying one rule: You must apply all 7 rules. A device may match Rule 5 (Class A) and Rule 3 (Class C) — the higher class applies.
2. Incorrect intended purpose: A vague or overly narrow intended purpose leads to incorrect classification. Define the intended purpose precisely and completely.
3. Ignoring software: If your IVD includes software that interprets results or makes diagnostic recommendations, the software classification may differ from the hardware.
4. Forgetting accessories and control materials: Calibrators and control materials inherit the classification of the device they support. Do not classify them independently.
5. Not considering self-testing provisions: A device intended for both professional and layperson use must be classified for both use scenarios — the higher class applies.
6. Assuming pre-IVDD classification is still valid: Many devices classified as "self-certified" under IVDD are now Class B or C. Do not carry forward old classifications.

Action Plan for Manufacturers

If you are classifying a new IVD or re-evaluating an existing one under the IVDR:

1. Document the intended purpose in detail — analyte, specimen, clinical context, user type
2. Walk through all 7 rules in Annex VIII and document which rules apply and why
3. Apply implementing rules to resolve multi-rule scenarios
4. Consult MDCG 2020-16 rev.3 for guidance on ambiguous cases
5. Document your rationale — this will be reviewed by your Notified Body
6. Monitor the simplification proposal for potential changes that may affect your classification
7. Engage with your Notified Body early if your classification is borderline or uncertain

Correct classification is the foundation of your entire IVDR compliance strategy. Invest the time to get it right — the cost of getting it wrong far exceeds the cost of a thorough analysis upfront.