IQ OQ PQ is the acronym for the three core stages of qualification of equipment, facilities, utilities and systems in GMP: Installation Qualification, Operational Qualification and Performance Qualification. Understanding the meaning of IQ OQ PQ is not a theoretical exercise: it is the basis for demonstrating, with documented evidence, that a piece of equipment is correctly installed, operates as designed and delivers compliant results under real operating conditions. In this guide we look at what each stage requires under Annex 15 of EudraLex Volume 4, how URS, DQ, FAT and SAT connect to them, which documents you need and which mistakes inspectors challenge most often.
IQ OQ PQ meaning and position in the qualification life cycle
The three stages do not exist in isolation: they are part of a life cycle that Annex 15 (in operation since 1 October 2015) describes in a logical sequence. Everything starts with the URS (User Requirements Specification), the document that defines user requirements and remains a point of reference throughout the validation life cycle: quality needs to be built in at this stage. Next comes DQ (Design Qualification), which demonstrates and documents that the design complies with GMP and with the URS requirements.
Before delivery, FAT (Factory Acceptance Testing) and SAT (Site Acceptance Testing) may take place: Annex 15 allows tests and documentation reviews to be performed at the vendor and, where functionality is not affected by transport and installation, not to be repeated at IQ/OQ. Only then do the three stages that give the acronym its name come into play:
- IQ – Installation Qualification: documented verification of correct installation;
- OQ – Operational Qualification: verification that the system operates as designed across the operating range;
- PQ – Performance Qualification: verification of performance under real process conditions.
The stages compared: objectives, references and outputs
| Stage | Objective | Annex 15 reference | Typical outputs |
|---|---|---|---|
| URS | Define user and quality requirements | § 3.2 | User Requirements Specification |
| DQ | Demonstrate design compliance with GMP and the URS | § 3.3 | Design Qualification report |
| FAT / SAT | Test the equipment at the vendor and after delivery | § 3.4–3.7 | FAT/SAT protocols and reports |
| IQ | Verify installation, components, calibration, materials | § 3.8–3.9 | IQ protocol and report, instrument list |
| OQ | Confirm operation as designed, including operating limits | § 3.10–3.12 | OQ protocol and report, finalised SOPs |
| PQ | Demonstrate consistent performance under real conditions of use | § 3.13–3.14 | PQ protocol and report |
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IQ – Installation Qualification: what to actually verify
IQ (§ 3.8–3.9 of Annex 15) is the documented verification that equipment, facilities, utilities or systems are installed in line with design and specifications. As a minimum it should include:
- verification of the correct installation of components, instrumentation, services and pipework against drawings and specifications;
- collection and verification of supplier operating and maintenance instructions;
- calibration of instrumentation;
- verification of materials of construction.
A classic mistake is treating IQ as a box-ticking formality: during inspections, an incomplete instrument list or calibrations not traceable to reference standards are frequent — and easily avoidable — findings.
OQ – Operational Qualification: operating limits matter
OQ (§ 3.10–3.12) normally follows IQ, but may be performed as a combined IOQ where justified. It must include tests developed from knowledge of processes, systems and equipment, designed to demonstrate that the system operates as designed, and tests covering upper and lower operating limits — the so-called "worst case" conditions, where applicable. Completing OQ is not just a signed report: Annex 15 links it to the finalisation of operating and cleaning procedures, operator training and preventive maintenance requirements.
PQ – Performance Qualification: real process conditions
PQ (§ 3.13–3.14) normally follows the successful completion of IQ and OQ, although in some cases it may be performed together with OQ or with process validation. Tests must use production materials, qualified substitutes or simulated product with equivalent behaviour under normal operating conditions, covering the operating range of the intended process. This is the stage that answers the inspector's question: "does this system, used the way you actually use it, deliver consistent, compliant results?"
IQ OQ PQ in the international context: PIC/S and FDA
The URS–DQ–IQ–OQ–PQ model is shared internationally, with nuances. On 30 July 2026 PIC/S published the revision of its Recommendations on Qualification and Validation (PI 006-4), entering into force on 1 October 2026 and consolidating into a single document the previous guidance on Validation Master Plans, IQ/OQ, non-sterile process validation and cleaning validation. The FDA, in its 2011 guidance "Process Validation: General Principles and Practices", frames equipment qualification within Stage 2 (Process Qualification) of a lifecycle approach. If your site is inspected by multiple authorities, aligning internal terminology with these references avoids pointless debates during audits.
Typical mistakes to avoid in audits
- Weak or missing URS: without clear requirements, DQ and PQ have no reference to verify against.
- Copying vendor protocols without assessing their adequacy for the intended use.
- Vague acceptance criteria ("runs smoothly") that are neither measurable nor defensible.
- Unmanaged qualification deviations: every discrepancy must be documented, assessed and closed before moving to the next stage.
- No link to change control: qualification does not end with PQ — it must be maintained over time.
GuideGxP recommendation
The fastest way to make qualification defensible in audits is to work "matrix-first": a traceability matrix linking every URS requirement to the DQ, IQ, OQ and PQ tests that verify it. Define the approach, responsibilities and acceptance criteria in a Validation Master Plan before writing protocols, manage qualification deviations formally and plan the periodic review from day one. And remember: a qualification report must be readable — and defensible — even by someone who was not there when the tests were run.
To go beyond the theory: our Operational Guide to GMP Annexes 1, 15, 16 and 20 – With Best Practices dedicates an entire section to Annex 15, qualification and validation, with ready-to-use checklists and best practices for IQ, OQ and PQ.
