GSS coding system
GSS codes are nine-character geocodes maintained by the United Kingdom's Office for National Statistics to represent a wide range of geographical areas of the UK, for use in tabulating census and other statistical data. GSS refers to the Government Statistical Service of which ONS is part.
GSS codes replaced a previous system called ONS codes from January 2011. ONS codes were hierarchical whereas in GSS codes there is no relation between the code for a lower-tier area and the corresponding parent area.
Code formulation
GSS codes have a fixed length code of nine characters. The first three characters indicate the level of geography, and the six digits following define the individual unit. For example, the Royal Borough of Greenwich is coded asE09000011, Middlesbrough is E06000002, Cambridge E07000008 and Fenland E07000010., the meanings of some common three character prefixes are as follows:
| England | Wales | Scotland | Northern Ireland | Other | Status | Entity |
| E00 | W00 | S00 | N00 | - | Current | Census Output Area ; Small Areas |
| E01 | W01 | S01 | – | - | Current | Lower layer Super Output Area ; Data Zone |
| E02 | W02 | S02 | – | - | Current | Middle layer Super Output Area ; Intermediate Zone |
| E04 | W04 | S35 | – | - | Current | Civil Parish ; Community |
| E05 | W05 | S13 | N08 | - | Current | Ward or Electoral Division |
| E06 | W06 | S12 | – | - | Current | Unitary Authority |
| E07 | – | – | – | - | Current | Non-Metropolitan District |
| E08 | – | – | – | - | Current | Metropolitan Borough |
| E09 | – | – | – | - | Current | London Borough |
| E10 | – | – | – | - | Current | County |
| E11 | – | – | – | - | Current | Metropolitan County |
| E12 | – | – | – | - | Current | English Region |
| E13 | – | – | – | - | Current | Inner and Outer London |
| E14 | W07 | S14 | N06 | - | Current | Westminster Parliamentary Constituency |
| E15 | W08 | S15 | N07 | - | Current | European Electoral Region |
| E16 | - | - | - | - | Archived | Primary Care Trusts |
| E17 | - | - | - | - | Archived | Care Trusts |
| E18 | - | - | - | L00 / M00 | Archived | Strategic Health Authorities |
| E19 | - | - | - | - | Archived | Pan Strategic Health Authorities |
| E20 | W12 | - | - | - | Current | Cancer Registries |
| E21 | W13 | - | - | - | Archived | Cancer Networks |
| E22 | W14 | - | - | - | Current | Community Safety Partnerships |
| E23 | W15 | S23 | N23 | - | Current | Police Force Areas |
| E24 | - | - | - | - | Archived | Local Learning and Skills Councils |
| E25 | - | - | - | - | Current | Primary Urban Areas |
| E26 | W18 | S21 | - | - | Current | National Parks |
| E27 | - | - | - | - | Archived | New Deal for Communities |
| E28 | W20 | - | - | - | Current | Registration Districts |
| E29 | W21 | - | - | - | Current | Registration Sub-District |
| E30 | W22 | S22 | N12 | K01 | Current | Travel to Work Areas |
| E31 | W25 | S38 | N31 | - | Current | Fire and Rescue Authorities |
| E32 | W09 | S16 | – | - | Current | London Assembly; Welsh Assembly; Scottish Parliament Constituency |
| E33 | W35 | S34 | N19 | - | Current | Workplace Zones |
| E34 | W37 | - | - | K05 | Archived | 2011 Built Up Areas |
| E35 | W38 | - | - | K06 | Archived | 2011 Built Up Area Sub-Divisions |
| E36 | W39 | - | - | - | Current | Census Merged Wards |
| E37 | - | - | - | - | Current | Local Enterprise Partnerships |
| E38 | - | - | - | - | Current | Clinical Commissioning Groups |
| E39 | - | - | - | - | Archived | NHS England |
| E40 | - | - | - | - | Current | NHS England Regions |
| E41 | W40 | - | - | - | Current | Merged Local Authority Districts |
| E42 | - | - | - | - | Current | Census Merged Counties |
| E43 | - | - | - | - | Current | Non-Civil Parished Areas |
| E45 | - | - | - | - | Current | Public Health England Centres |
| E46 | - | - | - | - | Current | Public Health England Regions |
| E47 | - | - | - | - | Current | Combined Authorities |
| E48 | - | - | - | - | Current | Local Resilience Forums |
| E49 | - | - | - | - | Current | Enterprise Zones |
| E50 | - | - | - | - | Current | Waste Authorities |
| E51 | - | - | - | - | Current | Development Corporations |
| E52 | - | - | - | - | Current | LEP - overlapping part |
| E53 | - | - | - | - | Current | LEP - non overlapping part |
| E54 | - | - | - | - | Current | Integrated care boards |
| E55 | - | - | - | - | Current | Strategic Clinical Networks |
| E56 | - | - | - | - | Current | Cancer Alliances |
| E57 | - | - | - | - | Archived | National Cancer Vanguards |
| E58 | - | - | - | - | Current | County Electoral Divisions |
| E59 | - | - | - | - | Current | Integrated Care Systems |
| E60 | W43 | S44 | N13 | - | Current | Local Planning Authorities |
| E61 | - | - | - | - | Current | Greater London Authority |
| E63 | W45 | S45 | K08 | Current | 2022 Built Up Areas | |
| E92 | W92 | S92 | N92 | L93 / M83 | Current | Country |
| E92 | W92 | S92 | N92 | - | Current | Country |
| - | - | - | - | J01 | Current | Major Towns and Cities |
| - | - | - | - | J02 | Current | 1961 Census Parishes |
| - | - | - | - | J03 | Current | 1961 Census Wards |
| - | - | - | - | J04 | Current | 1961 Census Districts |
| - | - | - | - | J05 | Current | 1961 Census Counties |
| - | - | - | - | K02 | Current | United Kingdom |
| - | - | - | - | K03 | Current | Great Britain |
| - | - | - | - | K04 | Current | England and Wales |
| - | - | - | - | L93 / M83 | Current | British Crown Dependencies |
| - | - | - | - | M01 | Current | Primary Healthcare Directorate |
| - | - | - | N09 | - | Current | Local Government Districts |
| - | - | - | N10 | - | Current | District Election Areas |
| - | - | - | N11 | - | Current | Settlement 2015 |
| - | - | - | N24 | - | Current | Police Force Districts |
| - | - | - | N32 | - | Current | Northern Ireland Fire and Rescue Service Areas |
| - | - | - | N33 | - | Current | Northern Ireland Fire and Rescue Service Districts |
| - | - | - | N34 | - | Current | City Regions |
| - | - | S03 | - | - | Archived | Community Health Partnerships |
| - | - | S04 | - | - | Current | Regeneration Outcome Agreement Areas - Scotland |
| - | - | S05 | - | - | Current | Regeneration Outcome Areas - Community Planning Partnerships |
| - | - | S06 | - | - | Current | Regeneration Outcome Areas - Local Areas |
| - | - | S07 | - | - | Current | Regional Transport Partnerships |
| - | - | S08 | - | - | Current | Health Board areas |
| - | - | S09 | - | - | Current | Enterprise Regions |
| - | - | S10 | - | - | Current | Urban Regeneration Companies |
| - | - | S11 | - | - | Current | Strategic Development Plan Areas |
| - | - | S12 | - | - | Current | Council Areas |
| – | W10 | S17 | – | - | Current | Welsh Assembly; Scottish Parliament Electoral Region |
| - | - | S19 | - | - | Current | Localities |
| - | - | S20 | - | - | Current | Settlements |
| - | - | S24 | - | - | Current | Highlands and Islands Enterprise |
| - | - | S25 | - | - | Current | Community Justice Authorities |
| - | - | S26 | - | - | Archived | Community Health Partnerships sub-areas |
| - | - | S27 | - | - | Current | ISD Health Board of Treatment |
| - | - | S28 | - | - | Current | Census Detailed Characteristics |
| - | - | S29 | - | - | Current | Census Local Characteristics |
| - | - | S30 | - | - | Current | Local Administrative Units 1 |
| - | - | S31 | - | - | Current | Local Administrative Units 2 |
| - | - | S32 | - | - | Current | Scottish Police Divisions |
| - | - | S33 | - | - | Current | Broad Rental Market Areas |
| - | - | S35 | - | - | Current | Civil Parish |
| - | - | S36 | - | - | Current | Island Groups |
| - | - | S37 | - | - | Current | Integration Authorities |
| - | - | S39 | - | - | Current | Scottish Fire and Rescue Local Senior Officer Areas |
| - | - | S40 | - | - | Current | Scottish Fire and Rescue Service Delivery Areas |
| - | - | S41 | - | - | Current | Scottish Marine Regions |
| - | - | S42 | - | - | Current | Scottish Local Resilience Partnerships |
| - | - | S43 | - | - | Current | Scottish Regional Resilience Partnerships |
| - | W03 | - | – | - | Current | Upper layer Super Output Area |
| - | W04 | - | – | - | Current | Communities |
| - | W11 | - | – | - | Current | Local Health Boards |
| - | W16 | - | – | - | Current | Department for Children, Education, Lifelong Learning and Skills |
| - | W19 | - | – | - | Current | National Assembly Economic Regions |
| - | W23 | - | – | - | Current | Spatial Plan Areas |
| - | W24 | - | – | - | Current | Spatial Plan Sub-areas |
| - | W26 | - | – | - | Current | Strategic Regeneration Areas |
| - | W27 | - | – | - | Current | Strategic Regeneration Sub-areas |
| - | W28 | - | – | - | Current | Transport Consortia Areas |
| - | W29 | - | – | - | Current | Agricultural Regions |
| - | W30 | - | – | - | Current | Agricultural Small Areas |
| - | W31 | - | – | - | Current | Non-National Park Area |
| - | W32 | - | – | - | Current | Non-Strategic Regeneration Area |
| - | W33 | - | – | - | Current | Communities First Areas |
| - | W34 | - | – | - | Current | Non-Communities First Areas |
| - | W36 | - | – | - | Current | Footprint Regions for Public Service Collaboration |
| - | W42 | - | – | - | Current | City Regions |
In 2019, the House of Commons Library proposed names instead of numeric codes for MSOAs to make them easier to use. In 2021 the library created names for MSOAs for use within the house.
A full listing of GSS names and codes may be found by following the link to ONS Geography's Code History Database, below.