The deadline for claiming a refund passed on September 30, after having been extended several times after people were slow to get their cash.

Before motorists could get their refund, the government charged an administration fee of $8.

If, after the fee was levied, the refund was $10 or less, then those drivers weren't eligible for any cash.

According to government figures, there were 18,709 policies in the Illawarra where residents did not claim the refund.

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Of those, 6525 - 34 per cent - were $20 or less. And a sizeable proportion of these would have been under the $10 threshold once the fee was applied.

These policies accounted for around 10 per cent of the $773,148.79 left unclaimed across the Illawarra.

The Wollongong 2500 postcode had the most unclaimed revenue, with $150,472.19.

The lowest was the University of Wollongong's 2522 postcode with just $317 from six policy holders.

"More than $9.6 million was claimed by 160,555 eligible policyholders in the Wollongong Council LGA, accounting for 85 per cent of eligible policyholders," said Customer Service Minister Victor Dominello.

The Minister also said the leftover funds wouldn't be headed for the government coffers.

"Any unclaimed money will go towards reducing Green Slips, by lowering the motor accidents levy," Mr Dominello said.