Here's how to get your slice of $5.85m the Illawarra's owed

Or who knows, it could be an unexpected windfall from a relative's will - either way, Revenue NSW is here to help.

A whopping $21.8 million in "unclaimed money" has been returned to NSW households and businesses this financial year.

But there's still a stockpile of $234 million still looking for the right home.

Of that, more than 21,000 claims are linked to the Illawarra - totalling a significant $5.853 million.

Almost $1.4m in payments and over-payments to $856,000 in dividends and $150,000 in superannuation is waiting for collection.

The majority of that money is linked to the 2500 postcode ($1.365m) but 2502 and 2518 feature too.

Outside of Sydney, only Newcastle and Lake Macquarie

"Unclaimed money" takes many forms. It can be payments, refunds, unpresented cheques, dividends and the money that goes astray when people move, die, change their name or lose paperwork.

Revenue NSW holds those payments but tries to get the money to the correct individual. Last year the department sent letters to more than 11,000 people in the home of finding the right home for $8 million.

But only around a quarter of that was ultimately returned.

You will be able to make a claim through the NSW Revenue portal.

It is free to make a claim but it's also important to have the right documents before claiming so you can be verified as the owner.

Once you've provided satisfactory ownership to the money, you should expect to receive an outcome within 28 days.

If you cannot lodge your claim online, you can download the Unclaimed Money Claim Form, and then email the completed form with all supporting documentation.