Format
An NHI number has a specific format. It is 7 characters in length and contains a check digit. This format consists of 3 alphabetic characters being in the range of A-Z, excluding I and O, and 4 numeric characters being in the range 0-9. The 4th numeric character is the check digit. The assignment of the first 6 characters is arbitrary and bears no relationship to the individual to whom it is assigned.
The NHI Number is most often represented with the alphabetic characters upper case.
NHI Numbers are often referred to as being valid or invalid. Any NHI Number that does not fit the correct format or that has an incorrect check digit is referred to as invalid. Usually reference to an NHI Number being valid or not does not indicate that it is correctly associated with the right individual. As the identifier is arbitrary there is no way to do this based solely on the identifier itself.
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