Australians are being urged to check for any lost super, with $17.5 billion unclaimed nationwide.

The Australian Taxation Office revealed on Friday that one NSW account holder alone has more than $2 million waiting to be claimed.

"Our data shows there are some large amounts still lost," said ATO Assistant Commissioner Graham Whyte said.

In the last financial year, $420 million worth of super funds were reunited with their owners.

But there's still $17.5 billion unclaimed.

Mr Whyte said people often lose contact with their super funds when they change jobs, move house, or simply forget to update their details.

A list of the top ten postcodes with the highest amount of lost and unclaimed super:

1. 4740, QLD - $60.1 million unclaimed

2. 2170, NSW - $59.2mln

3. 4870, QLD - $57.5mln

4. 3030, Vic - $56.7mln

5. 4350, Qld - $53.3mln

6. 2560, NSW - $50.2mln

7. 2010, NSW - $45.7mln