Over $146 million in forgotten money is sitting with Revenue NSW, including money from share dividends, trust accounts, deceased estates and overpayments.
The missing money hasn't been returned to its owners because their contact details have changed and they can't be tracked down.
The money waiting to be claimed ranges from $20 in share dividends to a trust fund worth more than $1 million.
To check if you have unclaimed money, visit the free search tool on the Revenue NSW website.
Minister for Finance and Small Business Damien Tudehope said cost of living is a major issue facing families across NSW, which is why the NSW Government wants people to check their eligibility.
"It only takes a few minutes and you could walk away with extra money in your pocket," Mr Tudehope said.
The NSW Government will hold the money indefinitely until it is claimed.
