A number used to identify a PERSON uniquely within the NHS in England and Wales.

UK Government Data Standards Catalogue (GDSC), Version 2.0, Agreed 01.01.02. GDSC:

This will not vary by any Organisation of which a PERSON is a PATIENT.

It is mandatory to record the NHS NUMBER for each PATIENT. The exception to this rule is A&E care. The NHS NUMBER, the primary identifier of a PERSON, is a unique identifier for the PATIENT.

The NHS NUMBER is 10 numeric digits in length. The tenth digit is a check digit used to confirm its validity. The check digit is validated using the Modulus 11 algorithm and the use of this algorithm is mandatory. There are 5 steps in the validation of the check digit:

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.

If the result is 11 then a check digit of 0 is used. If the result is 10 then the NHS NUMBER is invalid and not used.

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

NHS Strategic Tracing Service: http://www.nhsia.nhs.uk/nsts/pages/faq.asp


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