New Zealand clinical coding conventions

Morbidity data is collected in New Zealand using The International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, Australian Modification (ICD-10-AM), The Australian Classification of Health Interventions (ACHI) and The Australian Coding Standards (ACS).

The rules and conventions of ICD-10-AM/ACHI/ACS govern clinical coding practice and underpin consistency and accuracy of clinical coded information submitted to the National Collection – National Minimum Dataset.

A New Zealand Convention is an additional requirement that clinical coders are required to follow. The conventions are developed and defined by the Ministry of Health in collaboration with relevant stakeholder groups.

New Zealand conventions
Australian Coding Standard (ACS) New Zealand Convention (NZC)
ACS 0029 Coding of Contracted Procedures
Updated 1 July 2014
This standard relates to hospital treatment being carried out under contracting or subcontracting arrangements between two hospitals. The standard states ‘all procedures carried out under the contract are to be recorded and coded in both hospitals. The hospital not carrying out the procedure should flag the appropriate code’. However, the standard does say 'clinical coders should be familiar with their respective state/territory methods of reporting contracting information'.

In New Zealand only one hospital is to record and code the treatment provided under the contract arrangement and report to the National Minimum Dataset (NMDS). Where the hospital is a private hospital, it is preferred that the public hospital reports the event. However, the contract arrangement should specify the hospital that will be responsible for reporting the event to the NMDS.

Contracted events must be reported to the NMDS with the appropriate agency, facility code and meet the 21-day reporting requirement.

Refer to the New Zealand Casemix Framework for Publicly Funded Hospitals, WIESNZ17 Methodology 2017/18 v1.2 June 2017, 5.2.37 Designated Hospital for Casemix Revenue

Procedures performed at another hospital during an inpatient episode of care (transfers)

Effective Mar 2009
Updated Jul 2014

Prior to the implementation of the national collection – National Non-Admitted Patient Collection (NNPAC) advice previously provided was to capture the outpatient event/treatment (provided at another hospital/DHB) as part of the inpatient event and report it to the National Minimum Dataset (NMDS). The principle underpinning this advice was that it was of value to collect the outpatient event/treatment in the national collections than not at all. This practice was adopted by the DHBs across New Zealand and formed part of their NMDS clinical coding.

However, as NNPAC has evolved it is able to collect information across a large number of outpatient purchase units and there is a high chance that the outpatient event/treatment will be reported to both collections (NMDS and NNPAC), which would result in duplicate reporting. This is a risk because it will affect Inter District Flow (IDF) funding for the DHBs and will overestimate the volume of activity occurring across the sector, therefore guidelines have been developed.


  • Each hospital will only report to the national collections the service/treatment they provide to the patient. Do not report the service/treatment provided by another public hospital/DHB (they will do their own reporting)
  • If a patient is transferred (not discharged) during an episode of care to a private facility for investigations/treatment and transfers back to the DHB the same day, the DHB should report the procedure(s) performed at the private facility in the DHB inpatient episode of care in accordance with the Australian Coding Standards (ACS).
ACS 0032 Allied Health Intervention There is no mandatory requirement in New Zealand to report allied health interventions to the National Minimum Dataset (NMDS). Reporting allied health interventions to the NMDS is optional.
ACS 0233 Morphology Reporting morphology to the National Minimum Dataset (NMDS) is not a mandatory requirement in New Zealand. Morphology information is collected directly by the New Zealand Cancer Registry (NZCR).

Reporting morphology to the NMDS is optional.
ACS 0503 Drug, Alcohol and Tobacco Use Disorders Z71.6 Counselling for tobacco use disorder is a New Zealand convention related to the mandatory reporting requirements aligned to the Health Target ‘Better help for smokers to quit’.

For more information, read New Zealand Convention on Counselling for Tobacco Use Disorder.
ACS 2001
External Cause Code Use and Sequencing

ACS 0026
Admission for Clinical Trial, Drug Challenge or Therapeutic Drug Monitoring
Z03.6 Observation for suspected toxic effect from ingested substance requires the assignment of external causes to identify the specific substance. This is a mandatory requirement in New Zealand as specified in the NMDS Data Dictionary.
Single Spontaneous Vaginal Delivery In New Zealand the intervention code 90467-00 [1336] Spontaneous vertex delivery must be assigned for all cases of normal vaginal delivery.

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