Three in every 100 £1 coins are fake, according to the latest survey by the Royal Mint. In a sample it found 3.09% of coins were counterfeit, up from 2.94% in its previous survey. With around 44m fakes in circulation it is highly likely one will pass through your hands at some point – but how do you know if it has?

"It is important for people to check their change," a Royal Mint spokesman says. He points to pages on the Mint's website which have details of how to spot a dud. Giveaways include the date and design on the reverse not matching (the reverse design is changed each year – who knew?), the milled edge being poorly defined, and uneven lettering. You should also note its appearance – it may be far shinier than the date on it suggests it should be.

If your change rings alarm bells, you should ask the person who handed it over to give you a different coin, because once it's in your pocket you shouldn't spend it – it is illegal to do so. What you should do, says the Mint's spokesman, is take it to the police, "that way we can find out where the hotspots are". Sadly the police will not give you a genuine £1 coin in return.