It means retirement savings between an Australian complying superannuation fund which is regulated by APRA, can be moved into a New Zealand KiwiSaver scheme, and vice versa.
It's important because it means tax payers won't have to hold accounts in both countries, and pay the fees and charges associated with them, by consolidating their savings, if they want to.
The Superannuation Legislation Amendment (New Zealand Arrangement) Bill 2012 was passed by the Australian Parliament today.
The Association for Superannuation Funds in Australia (ASFA) says "The ability of Australians and New Zealanders to transfer retirement savings between the two countries through the trans-Tasman retirement savings portability scheme recognises in legislation that our countries are becoming increasingly closer economically and socially."
It comes as the Closer Economic Relations Trade Agreement with New Zealand reaches its 30th anniversary next year, in which Financial Services and Superannuation Minister Bill Shortern said "This legislation is an important step towards our closer economic relations with New Zealand. It supports progress toward the goal of a single economic market, to which the Australian and New Zealand Governments are both committed."
483,400 Australian residents were born in New Zealand.
50,000 of them moved into Australia in the last year, while 14,000 people living in Australia moved across the Tasman over the same period.
The legislation is scheduled to commence on 1 July 2013.