Interoperability
Interoperability standards in the NHS: a map for hospital teams
NHS interoperability rests on a few layers: exchange standards (FHIR with UK Core, and HL7 v2 in many hospital feeds), shared terminology (SNOMED CT and dm+d), a shared identity (the NHS Number and the Personal Demographics Service), and the clinical safety standards DCB0129 and DCB0160, which are mandatory under the Health and Social Care Act 2012.
What NHS England means by interoperability
NHS England defines it as people involved in giving and receiving care being able to complete a task across software and organisational boundaries, using equipment and systems from different vendors that work together with minimal or no human intervention. It's a definition about getting work done, not just about connecting systems.
Exchange: FHIR, UK Core and HL7 v2
NHS England says the NHS uses FHIR UK Core to make integration with APIs and services easier, and publishes an API catalogue of national APIs and API standards. UK Core is governed by information standard DAPB4020 and is based on FHIR R4. HL7 describes its older v2 messaging as prominent in inpatient settings, so many feeds between a hospital's PAS, lab, radiology and other systems still use it. NHS England also provides the Interoperability Toolkit (ITK), a set of national standards, frameworks and implementation guides.
Terminology: SNOMED CT and dm+d
All NHS healthcare providers in England must use SNOMED CT to capture clinical terms in electronic patient record systems. It's a national information standard and so a contractual requirement. NHS England Digital's example: clinical information in a discharge summary can go straight into the GP record without anyone re-typing it. The UK edition adds UK extensions, and the Dictionary of Medicines and Devices (dm+d) is one of UK Core's listed dependencies for medicines.
Identity: the NHS Number and PDS
The NHS Number is the national unique patient identifier: 10 digits, the last one a check digit, set by ISB 0149. The Personal Demographics Service (PDS) is the national master database of NHS patients in England, Wales and the Isle of Man. Its usage policy says use of PDS is mandatory if you access or manage patient demographic data, you must use the NHS Number to uniquely identify patients, and any local copy of demographics must be synchronised regularly with PDS.
Safety and assurance
NHS England's interoperability guidance names two standards whose compliance is mandatory under the Health and Social Care Act 2012: DCB0129 for manufacturers of health IT systems and DCB0160 for organisations deploying them. Buyers also assess digital health products with the Digital Technology Assessment Criteria (DTAC), and organisations with access to NHS patient data and systems complete the Data Security and Protection Toolkit (DSPT). To find any other nationally recognised standard, use the NHS Standards Directory.
What it does not mean
- Using FHIR doesn't make two systems interoperable. They also need the same profiles, terminology and identifiers, which is what UK Core, SNOMED CT and the NHS Number provide.
- The NHS doesn't run one national system. NHS England stresses that it's hundreds of organisations using different systems, which is why the standards matter.
- Standards aren't optional extras. Several are information standards under section 250 of the Health and Social Care Act 2012, and the clinical safety pair is mandatory.
Where Thalix fits
Thalix speaks the exchange layer: HL7 v2, FHIR R4 (including SMART Backend Services), DICOMweb for imaging, MQTT for bedside and building sensors, IEEE 11073 SDC through an external gateway, webhooks and files. It links every identifier a source gives (hospital number, NHS Number, FHIR id, device assignment) to one Thalix patient and raises conflicts for review. It doesn't replace national services such as PDS, and we don't claim UK Core conformance or any assurance result today.
Thalix is at pilot stage. Demos run on synthetic data, and a hospital deployment needs its own clinical safety case, information governance approval and security review. We don't claim any certification or assessment result the product doesn't have.
Questions people ask
Is SNOMED CT mandatory in NHS hospitals?
Yes. NHS England Digital says all NHS healthcare providers in England must now use SNOMED CT for capturing clinical terms within electronic patient record systems; it's a national information standard and a contractual requirement.
Which interoperability standards are mandatory by law?
NHS England's interoperability guidance says compliance with DCB0129 and DCB0160 is mandatory under the Health and Social Care Act 2012. Other information standards, such as UK Core governance and the NHS Number, are also published under section 250 of that Act.
Where can I look up NHS data and interoperability standards?
NHS England points to the NHS Standards Directory (standards.nhs.uk), which lists nationally recognised standards for health and adult social care.
Sources
Each source below is an official page, read and checked in October 2026. Where a page and this guide differ, the official page wins.
- Interoperability NHS England · checked October 2026
- UK Core FHIR Release 4: Governance (DAPB4020) NHS England, NHS Standards Directory · checked October 2026
- SNOMED CT NHS England Digital · checked October 2026
- NHS numbers for health and social care organisations NHS England Digital · checked October 2026
- Personal Demographics Service NHS England Digital · checked October 2026
- Comparison: HL7 v2 messaging (FHIR R5) HL7 · checked October 2026
General information only, written for hospital digital, IT, operations and clinical safety teams. It isn't legal, regulatory, information governance or clinical safety advice, and it doesn't replace your own organisation's processes or the official guidance linked above.