NHS Number

Change History
DSCN 2025 / 01	Audiology Wait Times Data Set
DSCN 2024 / 12	Welsh Emergency Care Data Set
DSCN 2022 / 06	Main Specialty (Consultant) (AMD)
DSCN 2021 / 01	Single Cancer Pathway – Adjustments Data Set – Retirement
DSCN 2020 / 31	National Cancer Data Standards for Wales – Systemic Anti-Cancer Therapy (SACT)
DSCN 2020 / 28	Suspected Cancer Pathway – Core (AMD)
DSCN 2020 / 22	Single Cancer Pathway - Adjustments
DSCN 2020 / 21	Single Cancer Pathway - Core
DSCN 2020 / 02	Maternity Indicators Data Set (AMD)
DSCN 2019 / 09	National Cancer Data Standards for Wales – Core
DSCN 2016 / 02	Maternity Indicators Data Set
DSCN 2015 / 06	NHS Number Operational Standard
DSCN 2015 / 03	Radiotherapy Data Set
DDCN 2014 / 05	Cancelled Admitted Procedures (Postponed Admitted Procedures) Data Set
DSCN 2014 / 02	Substance Misuse Data Set
DSCN 2013 / 03	Cancelled Admitted Procedures Data Set
DSCN 2012 / 11	Elective Admission List Data Set (EAL Ds)
DDCN 2012 / 06	To remove all references to 'Health Solutions Wales', 'Business Services Centre' and 'Information Products Unit' and replace with 'NHS Wales Informatics Service'
DSCN (2009) 02 (W)	Emergency Department Data Set
DSCN 10/03 (W)	NHS Numbers for Babies

This data item is / was included in the following data sets / collections between the dates shown:

Data Set / Collection	Valid From	Valid To
APC ds99	1^st April 1999
EAL ds	1^st April 1999	21^st November 2012
OP ds	1^st April 1999
CC ds	1^st April 2007
OPR ds	1^st July 2008
EDDS	1^st April 2009
PAP ds	1^st April 2013
SM ds	1^st April 2014
RTDS	1^st April 2014
MI ds	1^st April 2016
SCPC ds	1^st January 2021
SCPA ds	1st January 2021	3rd February 2021
National Cancer Ds – Core
National Cancer Ds - SACT
WECDS	1^st August 2024
AUD WT ds	1^st April 2025

The NHS number is the primary identifier of a person, and is a unique identifier for a patient within the NHS in Wales.

It is mandatory to record the NHS Number

• (in the MI ds) for each woman and baby

• (in every other data set) for each patient registered with a GP practice in England and Wales.

The NHS number is allocated to an individual, to enable unique identification for NHS health care purposes.

The MI ds captures data relating to the woman at initial assessment and to mother and baby for all births. Each Health Board makes data available in relation to the events which they managed, and initial assessment and birth data will be linked nationally regardless of whether both events took place in the same or at different health boards. The NHS number is needed on each record to enable this data to be linked.

This NHS Number format was mandated for use effective 1^st November 1997. Prior to this, the NHS Number was an alphanumeric code which ranged in size from 10 – 17 characters.

If known, the patient’s Health and Care Number should be used to populate this field for patients resident in Northern Ireland.

If known, the patient’s Community Health Index (CHI) Number should be used to populate this field for patients resident in Scotland.

Format: 10 digit numeric

See Health and Care Number

See Community Health Index (CHI) Number

Check Digit Algorithm

(This algorithm applies to the Welsh and English NHS Number and the Northern Ireland Health & Care Number. The check digit algorithm for the Scottish CHI Number is available on request from the NHS Wales Informatics Service.)

Step 1 Multiply each of the first nine digits by a weighting factor as follows:

Digit Position (starting from the left)	Factor
1	10
2	9
3	8
4	7
5	6
6	5
7	4
8	3
9	2

Step 2 Add the results of each multiplication together

Step 3 Divide the total by 11 and establish the remainder

Step 4 Subtract the remainder from 11 to give the check digit

Step 5 Check the remainder matches the check digit. If it does not, the number is invalid.

If the result of Step 4 is 11 then a check digit of 0 is used

If the result of Step 4 is 10 then the number is invalid and not used