The new 12-sided £1 coin will enter circulation on 28 March, the government has said. The round £1 will be legal tender alongside the new, more-secure coin until 15 October.
The public is being urged to use their current £1 coins or bank them before they lose their legal tender status. The government estimates around a third of the £1.3 billion worth of coins stored in piggy banks or saving jars around the UK are the current £1 style.
Some of those returned by the public will be melted down and used to make the 12-sided version. The new style was announced in the 2014 budget and has been billed by the Royal Mint as "the most secure coin in the world".