Unlike overseas migration, interstate migration in Australia is totally unregulated. It falls within the unwritten freedoms enjoyed by Australians to live wherever they please and to move from one address to another without being accountable to government. In the absence of regulation, however, problems arise when data is required on interstate movements - for example when updating the populations of the States. It has therefore always been necessary to estimate interstate arrivals and departures for this purpose. Currently the ABS uses information on interstate change of address advised to Medicare Australia and to the Department of Defence in the case of the military.

Age is in five year intervals.

As interstate migration is unregulated, there are no direct quarterly measures of arrivals and departures between the states and territories. Post-censal quarterly measurements of interstate migration are therefore estimates. These estimates are modelled using administrative by-product data which by nature are non-compulsory and have incomplete coverage.

Medicare data used to estimate NIM are adjusted by means of expansion factors. It is known that some people, particularly younger Medicare card holders, do not register changes of address with Medicare, or do so long after the fact. Expansion factors account for this under coverage of Medicare data by various ages and sex. For more information see the Information Paper; Review of Interstate Migration Method, linked below.

For information on the ABS Institutional Environment, see the link below.

On-line.