IVDR Annex VIII sets out seven classification rules, but Rule 3 alone runs across nine separate sub-points — sexually transmitted agents, infectious-disease risk, prenatal screening, companion diagnostics, cancer staging, and more. Buried in that list, sub-point (i) does something most of the others don't: it classifies a device as Class C for one reason alone — that it performs human genetic testing — independent of what disease area, sample type, or clinical context the test addresses.

What Rule 3 actually covers

Rule 3 sits functionally between Rule 2's Class D transfusion- and transplant-safety testing and the lower-risk rules, catching the next tier of risk — the long middle band of IVDs where an erroneous result has serious but not immediately catastrophic consequences. MDCG 2020-16 walks through all nine sub-points in detail; in practice, a handful decide most real classification questions for diagnostics companies.

  1. Detecting the presence of, or exposure to, a sexually transmitted agent.
  2. Detecting an infectious agent in cerebrospinal fluid or blood without a high or suspected high risk of propagation.
  3. Detecting an infectious agent where an erroneous result risks death or severe disability to the patient, foetus, embryo, or the patient's offspring.
  4. Prenatal screening of women to determine their immune status toward transmissible agents.
  5. Determining infective disease or immune status where an erroneous result risks a life-threatening management decision.
  6. Use as a companion diagnostic.
  7. Disease staging where an erroneous result risks a life-threatening management decision.
  8. Screening, diagnosis, or staging of cancer.
  9. Human genetic testing.

Why genetic testing can't fall back to Class B

Rule 1 sets IVDR's residual class: a device that doesn't meet any of the higher-risk rules' criteria lands at Class B by default. That is where a lot of diagnostics teams expect their test to sit — particularly if a comparable, non-genetic assay for the same indication already classifies at Class B. Rule 3(i) forecloses that path entirely. It doesn't ask what the test result is used for, what disease it addresses, or how severe a wrong answer would be; it asks only whether the device performs human genetic testing. A pharmacogenomic panel and an immunoassay measuring a related biomarker can end up in different classes for exactly that reason, even when the clinical stakes look comparable on paper.

A pharmacogenomic panel and an immunoassay for the same indication can land in different classes for one reason: one performs genetic testing and the other doesn't. Rule 3 doesn't ask what the result is used for — it asks what kind of test produced it. Why the Rule 3(i) default holds regardless of context

The companion-diagnostics sub-point sits right next to it

Rule 3(f) — companion diagnostics — lands at the same Class C as genetic testing, but it is not the same obligation. A companion diagnostic triggers the Article 48(3) consultation procedure: a scientific opinion from EMA for centrally authorized medicinal products, or a national competent authority otherwise, on the device's suitability to the specific medicinal product it supports. A genetic test that is not a companion diagnostic skips that consultation entirely. The two sub-points frequently overlap — a hereditary biomarker test that gates a targeted therapy is both a genetic test under (i) and a companion diagnostic under (f) — and when they do, classification alone (Class C either way) doesn't tell you whether the added consultation applies. That's a separate question, decided by (f), not by (i).

What a misjudged genetic-test classification costs you
  1. An underbuilt technical file. Teams that plan for Class B self-declaration-adjacent documentation have to rebuild toward Class C's fuller technical-documentation and performance-evaluation package.
  2. A missed consultation requirement. If the genetic test is also a companion diagnostic, the Article 48(3) consultation adds a review step that doesn't appear in a Class C checklist read in isolation.
  3. A compressed Notified Body timeline. Class C conformity assessment still requires Notified Body technical-documentation review; discovering the class late shortens the runway to address findings.
  4. A budget built for the wrong tier. Regulatory cost and resourcing plans built around a Class B assumption routinely underestimate what Class C's assessment route actually requires.

None of this is exotic once the rule is read correctly. It is a classification exercise: confirm the intended purpose against Rule 3's actual wording, check whether Rule 2 reaches the device first, and separately confirm whether the companion-diagnostics consultation applies. Companies that run that sequence before committing to a conformity-assessment budget rarely get surprised by it later. Our IVD regulatory strategy work, and our companion diagnostic development support where the two sub-points overlap, both start with getting this classification right.

Frequently asked questions

Does every genetic test default to Class C under IVDR?

Yes. Annex VIII Rule 3(i) classifies a device intended for human genetic testing as Class C independent of which other Rule 3 sub-point might otherwise apply, unless Rule 2's transfusion- and transplant-safety criteria — which reach Class D — apply instead. The genetic-testing sub-point does not look at disease area or sample type; it looks only at whether the device performs genetic testing.

Is a companion diagnostic automatically Class D under IVDR?

No. Companion diagnostics sit in Rule 3(f) at Class C, the same class as human genetic testing in Rule 3(i). What changes for a companion diagnostic is the added Article 48(3) consultation procedure — a scientific opinion from EMA or a national competent authority — not the classification itself. A genetic test that is also a companion diagnostic falls under both sub-points at once.

Can a self-testing genetic kit be classified lower than Class C?

No. IVDR's self-testing and near-patient-testing implementing rules in Annex VIII can raise a device's class relative to its professional-use counterpart; they do not lower a Rule 3(i) device below Class C. A genetic test intended for lay self-testing use starts at Class C and is evaluated for whether it should move higher, not lower.

Sources & further reading

  1. Regulation (EU) 2017/746 (IVDR), Annex VIII — Classification Rules. eur-lex.europa.eu
  2. Medical Device Coordination Group. MDCG 2020-16 — Guidance on Classification Rules for In Vitro Diagnostic Medical Devices under Regulation (EU) 2017/746. health.ec.europa.eu

This article is provided for general informational purposes and reflects the regulatory landscape as of October 2026. It is not legal or regulatory advice. Confirm current IVDR Annex VIII classification and Article 48(3) consultation requirements with the European Commission, your Notified Body, or qualified counsel before acting.