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The Higher Education Classification of Subjects (HECoS)

A new subject coding system - the Higher Education Classification of Subjects (HECoS) - has been developed to replace the JACS system.  

JACS is used by HESA and UCAS to classify subjects of study; the implementation of HECoS provides an opportunity for a far broader range of stakeholders to use a common subject coding system in the future.

View the HECoS vocabulary

The coding frame is a single flat list of subjects that ensures the categorisation of courses and modules is always performed at a consistent level.  Unlike JACS, the subject code identifiers are randomly generated to avoid the coding frame running out of space.

HECoS has been developed independently from JACS and therefore there is no direct mapping available between the coding frames. To assist providers in recoding courses from JACS to HECoS, we have produced two mapping documents to indicate suggested mappings that might be used:

Mappings from JACS3 to HECoS

Mappings from HECoS to JACS3

Common Aggregation Hierarchy

A Common Aggregation Hierarchy (CAH) has been developed to provide standard groupings that can be applied to both HECoS and JACS subjects allowing for consistent analysis across both coding frames. These aggregations provide continuity in subject analysis through the transition from JACS to the new scheme and to other schemes such as those used by QAA. This will improve consistency across the sector.

View the Common Aggregation Hierarchy

The CAH has been designed to act as a bridge between HECoS and JACS. These are, however, two distinct coding frames, with HECoS having been developed in part to allow for more robust coding to address inconsistencies in coding using the JACS framework. As such, analysis between HECoS and JACS using this Common Aggregation Hierarchy will only provide indicative comparisons for time series analysis.

Timescale and additional resources

HECoS will be implemented for the academic year starting in the autumn of 2019.

For UCAS this means that the first collection of HECoS data will be aligned to the collection of 2019 entry undergraduate course details, ahead of the launch of their search service.

The HESA implementation is planned to be a part of the Data Futures implementation for the 2019/20 reporting year. We will be publishing a fuller timeline soon.

Background to the development of HECoS

Work began on the development of a new subject coding system in 2013 led by HEDIIP and in consultation with the HE sector.  The project was borne out of a need to replace the JACS system to meet the needs of a broader group of stakeholders and to reflect the diverse and dynamic nature of Higher Education in the twenty-first century, and culminated in July 2016 in the publication of the subject code system now known as HECoS.  Further detail about its background and development can be found on the HEDIIP webpage.


If you have any questions or comments about HECoS, please email [email protected].