The NHI has enough numbers at the current rates of allocation to assign to people until 2025. The Ministry is working with the sector to introduce a change to the NHI numbering format  to extend the range of NHI numbers available.

This involves checking and (where necessary) upgrading the health sector’s IT systems which record NHI numbers to accept a new format. This work is underway now to allow time for these checks and any upgrades to take place.

At the moment, NHI numbers are a unique 7-character number in the format AAANNNC (3 alpha, 3 numeric and one numeric check digit). The new format will be AAANNAX (3 alpha, 2 numeric, 1 alpha and one alpha check digit). 

The first new format NHI number will be issued once the current allocation of numbers has been exhausted.

NHI numbers are issued sequentially on the first six characters, eg ZAA0067, ZAA0075, ZAA0083, ZAA0091, ZAA0105, ZAA0113, ZAA0121, ZAA0130, ZAA0148, ZAA0156 [...] ZAB0003, ZAB0011, ZAB0020, ZAB0038, ZAB0046, ZAB0054, ZAB0062 and so on.

This will change with the new format NHI numbers. NHI numbers will be issued in sequential order of the first letter and then a randomised allocation of the next 5 characters with the last character, an alpha check digit. All NHIs starting with A will be issued first, Bs next, Cs, and so on. Within the As the remaining characters would be in a random order, eg ALU18KZ, AUL78CF, ARM79XB, ATD33RD, ADH48ZJ [...] BGA66HA, BTX92DF, BMW47VV, BCN94BU.

The Test NHI system has new format NHI numbers that can be used for testing, eg ZZZ00AX, ZGT56KB, ZHS91BR, ZHW58CN, ZLV86AX.

More about NHI test data

What this means for the health and disability sector

Sector systems that use NHI numbers will need to make sure they can use both the current NHI numbering format (which is due to run out in a few years) and the new format, which will come into effect once the current allocation is exhausted.

Some systems may need to be upgraded, and it’s important that sufficient time is allowed for this work. We recommend that systems are ready to accommodate the new format by 1 July 2023, well ahead of the expected change-over data of 2025.

Changing to the alpha/numeric/alpha format and retaining the existing 7 character length is considered the option that will have the least impact on the sector, and is unlikely to require a change in most databases.

The Ministry will maintain (as far as practicable) a central register of commonly used health applications that have been updated to accommodate the new format. Vendors who have upgraded applications to the use the new format should let us know by emailing


The costs of upgrading any systems is expected to be an issue for the software vendors and software providers to determine. The NHI represents a fundamental health system standard.

More information