Check your change now: The 50c coin that could be worth $15,000 after Royal Australian Mint error

With tap-and-go and PayID now the norm, it’s not often you take a good look at the coins shoved at the bottom of your bag or deep in your pocket.

But it might be worth paying more attention to your change in the hope of finding a rare 50c coin worth almost $15,000.

Only two of the coins are believed to be in circulation.

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According to retailer Downies Collectables — which recently sold one of the rare coins for $14,750 — the 50c coin minted in 1988 with the standard coat of arms on its tails side instead of the special Bicentenary image is “excessively rare” and “eminently historic”.

All 50c coins minted in 1988 were supposed feature a First Fleet boat and the dates 1788-1988 to celebrate the country’s bicentenary.

At least two coins that are known were instead accidentally printed with the standard coat of arms.

“As is customary, the creation of a special one-year-only 50c commemorative meant that the standard coat of arms 50c was not struck for circulation, and was naturally not included in the proof or mint sets of that year either,” Downies Collectables said.

“Indeed, no 1988 coat of arms 50c coins should exist.”

The retailer said the error was created by the “accidental union of mismatched obverse and reverse dies (heads and tails side)”.

7NEWS.com.au has contacted the Royal Australian Mint for comment.

Aussies have also been urged to check their change for a rare $1 that just might be worth as much $3000.

Coin expert Joel Kandiah says an easy-to-miss “significant” error by the Royal Australian Mint has resulted in a batch of $1 coins skyrocketing in value.

Kandiah says the sought-after coin is now selling for between $300 and $3000 online, depending on its condition.

“In 2003, Australian coin collectors became aware of a significant coin error originating from the Royal Australian Mint,” Kandiah said.

“A batch of $1 dollar coins from the year 2000 had been mistakenly produced using the incorrect obverse die (the heads side) and subsequently entered circulation.

“Astonishingly, this error went unnoticed for a year or two.

“Instead of the intended design, the obverse of some 2000 $1 dollar coins had been minted using the Australian 10 cent obverse die.

“Given the mere 1.4-millimetre difference in diameter between the 10 cent and $1 coin, this peculiar mistake led to the creation of the legendary 2000 $1 ‘mule’ coin.”

Kandiah told 7NEWS.com.au that it’s believed there could be as many as 7000 of the rare coins in circulation.