The last batch of £1 coins bearing the face of the late Queen Elizabeth II is entering circulation, with more than 23 million of them destined for tills and people's pockets.
The Royal Mint said the release of the final Elizabeth II coins, dated 2021 and 2022, marks "a pivotal moment in British coinage history".
Alongside them, a further 7.5m new King Charles III coins are also entering circulation.
His face has been seen on UK coins since 2023, but only on £1 and 50p denominations so far.
Rebecca Morgan, director of commemorative coin at the Royal Mint, said: "As we release more of the King Charles III £1 coins into circulation alongside the final coins of Queen Elizabeth II, we're witnessing the physical representation of our monarchy's transition."
She said she hoped finding the new coins in your change could "spark a rewarding hobby" for some, with the Royal Mint encouraging people to check to see if they receive any in the coming weeks.
While the coins were struck up to four years ago, they are being issued now because of demand for £1 coins, the Royal Mint said.
The 2022 coins will become the rarest in circulation, they added, with 7.735 million of those being released.
There are about 24.7 billion coins in circulation across the UK, with the King's coins currently only making up 0.004% of those.
Some 2.975 million £1 coins featuring the King were released last August by the Royal Mint, based in Llantrisant, Rhondda Cynon Taf.
They feature an intricate bee design on the tails side, representing his love of nature.
They are one of eight new designs that will eventually appear on the nation's coins, from the 1p to the £2. The country's flora and fauna will feature on them all, with animals including the red squirrel, puffin and dormouse depicted.
While they are the same size and shape as previous coins, the new designs feature larger numbers to help children identify figures and learn to count.
The change of design followed the death of Queen Elizabeth in September 2022, and the accession to the throne of the new King.
All UK coins featuring the late Queen's profile remain legal tender and in active circulation, alongside her son's coins.
In general, coins usually last 20 years - so the Queen Elizabeth and King Charles coins will be in circulation together for some time to come.
The Royal Mint has made the circulating coinage of each of Britain's monarchs since Alfred the Great.