The Taxonomy Oversight Group (TOG) is a new cross-government group, working with the Central Digital and Data Office (CDDO) to approve and recommend taxonomies. TOG provides a forum for data management and subject matter experts to discuss best practice and provide clear recommendations and information for taxonomy users.


Taxonomies exist so that data can be classified.

They are used extensively across government and can take the form of:

  • complex and hierarchical structure, for example, UK Standard Industrial Classification (SIC)

  • flat "code lists", for example, Gender

They include taxonomies that are consistent with international frameworks, to allow for comparability internationally. Many will also have national breakdowns to reflect UK requirements. 

Taxonomy Oversight Group

Prior to TOG being established there has been no central governance for taxonomies in the UK. The Office for National Statistics (ONS) and the CDDO have launched TOG as a Government Data Architecture Community (GDAC) group. The group has been established to promote best practice by bringing data producers and users together. The ultimate aim of the group is to ensure that there is consistency in taxonomy use, and the way it is verified for use across government.

TOG seeks to:

  • provide a forum for cross-government conversations with taxonomy experts to address challenges

  • provide clarity on taxonomy governance

  • bring experts together to approve and enforce taxonomies in a consistent, transparent way

  • provide a central information resource for users of existing taxonomies and those wishing to create new taxonomies

TOG will not own taxonomies or provide international representation. Instead, TOG will ensure that owners for taxonomies endorsed by the group are identified, that they fulfil the functions of ownership responsibilities, and this is communicated to users.

TOG members are experts in managing data domains, reference data, taxonomies or metadata. They include representatives from the Department for Work and Pensions, Department for Education, local government, Parliament, Cabinet Office, Scottish Government, Department for Business, Energy and Industrial Strategy, and Welsh Government.

Smaller Task Groups, that are taxonomy subject-focused, have also been established to support the work of TOG on a finite basis. Membership includes subject matter experts representing departments from across government and academia.

Taxonomy Best Practice Framework

The Taxonomy Best Practice Framework is a product of TOG.

The framework provides guiding principles that can be used to determine whether a taxonomy is fit for purpose.

The principles include, amongst others, that a good taxonomy must have clear ownership and governance policies in place.  It must have an established revision and maintenance process and that it must, where possible, adopt and align to existing national and international standards.

Existing taxonomies are evaluated against the Taxonomy Best Practice Framework before being recommended by TOG for CDDO endorsement.