The new pound coin has become more common than its round predecessor, the Treasury has announced.
There are now more new 12-sided quids in circulation than circular pounds.
Ministers announced the landmark as they urged the public to continue to return their old coins.
The Exchequer Secretary to the Treasury, Andrew Jones, is visiting a coin storage facility in Belfast on Wednesday, where more than £350,000 worth of coins are processed and redistributed daily, to banks and businesses across Northern Ireland.
The old coins cease to be legal tender on October 15. The new version was introduced on March 28.
“To have more new coins in circulation than old at this point is great news,” said Mr Jones.
“However, with less than 100 days to go, the clock is ticking.
“We are urging the public to spend, bank or donate their old pound coins and asking businesses who are yet to do so, to update their systems before the old coin ceases to be legal tender.”
Chief executive and deputy master of the Royal Mint, Adam Lawrence, said: “The Royal Mint is very proud to have delivered the new 12-sided £1 coin and ensuring a smooth transition is now our top priority.
“We hope our announcement about the changeover point in July will encourage those businesses who have not yet upgraded their equipment to do so ahead of the October 15 deadline.”
The new 12-sided coin was brought in to tackle the rise of counterfeit coins, which cost businesses and the taxpayers across the UK millions of pounds every year.