NHS Postcode Directory


  1. The NHS Postcode Directory is maintained, on behalf of the Department of Health, by the Office for National Statistics (ONS). It contains a record for every postcode in the UK, Channel Islands and the Isle of Man, and associates each postcode with a variety of geographic information, including grid references, Primary Care Trusts and Strategic Health Authority codes. The file also includes pseudo postcodes covering defaults and overseas countries.

  2. The full and reduced versions of the NHS Postcode Directory are issued every quarter by the National Administrative Codes Service (NACS). A CD-ROM is sent to named recipients both inside the NHS and to other recipients licensed to use this data in support of the NHS. Both versions of the NHS Postcode Directory are also available via the NHSnet only.

  3. A full description of the NHS Postcode Directory and the NACS reduced postcode data files, can be found by using the NACS website (this is only available on the NHSnet). See ONS: Publication Information Contact Details.

  4. The ONS will supply, on request and at a cost, copies of the NHS Postcode Directory, on different media, in different formats and for selected extracts. Contact the ONS for details and charges. See Publication Information Contact Details.

  5. Postcodes
  6. All postcodes made available via NACS postcode files have been standardised to the eight character postcode format as used by the Royal Mail's Postal Address File (PAF). All NHS Organisations should ensure that they conform to the postcode format.

  7. Postcodes are of the general format :

  8. Character Position 1 2 3 4 5 6 7 8
    Format a a/n a/n a/n space n a a
    Coding Frame Outward Code space Inward Code
  9. The coding frame allows the use of digits 0 (zero) to 9 and the use of upper-case alpha characters; no special characters are allowed.
  10. The fifth character of all standard format postcodes is always a space, and separates the outward and inward parts of the postcode. The outward part of the postcode is left-justified and can contain 2, 3 or 4 characters, and is space-filled in character positions 3 and 4 where required. The inward part of the postcode is always 3 characters.

  11. The following table gives examples of typical postcodes :

    Character Position Allocated by Notes
    1 2 3 4 5 6 7 8    
    1 2 3 4 5 6 7 8    
    W 9       3 X X Royal Mail  
    D A 1     5 P L Royal Mail  
    M K 4 5   1 T E Royal Mail  
    Z Z 9 9   4 L Z NACS Pseudo Postcodes, Defaults and Overseas
  12. The "Scottish split postcode indicator" field was discontinued from the 1996/1 version of the NHS Postcode Directory. This value used to appear in the 8th character position of the postcode (the postcode field was then only 7 characters in length). The 'Alternative' version of the NHS Postcode Directory, showing postcodes containing this field, is available from the ONS.

  13. Strategic Health Authority/Local Health Board/Health Board Codes
  14. Strategic Health Authorities in England are indicated by their standard NACS codes (Q codes). Local Health Boards in Wales use five character codes commencing with a '6', and with the last two characters '00'. Health Boards in Scotland use a three character version of the Health Board code (range SA9 - SZ9). The four Northern Ireland Health Boards are indicated by their standard codes - ZE0, ZN0, ZS0, ZW0.

  15. No Strategic Health Authorities exist for the Channel Islands and the Isle of Man so notional (or dummy) Strategic Health Authority codes are used to identify postcodes from these locations. The default Pseudo health authority code of X98 is used to indicate pseudo postcodes (defaults and overseas).

  16. For further information on Strategic Health Authority, Local Health Board, and Health Board codes and their values, See ADMINISTRATIVE CODES.

  17. Related Products
  18. The ONS produce annually two related publications : ONS Geography User Guide 9 (The Area of Residence Classification) and ONS Geography User Guide 10 (The NHS Organisation Manual). These show a breakdown of Strategic Health Authorities by Local Government authorities and Electoral Wards. Copies are available from ONS. Electronic copies are also included in the full NHS Postcode Directory on CD-ROM as provided by NACS.

  19. ONS produce a version of the Postcode Directory that is based on a stable area base to facilitate time series analysis - the 1991-based Frozen Postcode Directory. This is available from the ONS.

  20. The NACS issues the full manuals on the CD-ROM each quarter. This ensures that any new customers receive the necessary information.

  21. Changes
  22. The ONS should be notified of any queries relating to the allocation of postcodes to Strategic Health Authorities or Primary Care Trusts. All such queries are investigated by ONS, and any agreed changes are included in the following edition of the NHS Postcode Directory. The monthly postcode corrections are also included on the NHSnet, see Publication Information Contact Details.

  23. Requests and suggestions for improvements to the NHS Postcode Directory or queries relating to its use should be directed to NACS, who are taking the lead on this product on behalf of the NHS; see Publication Information Contact Details.