The Federation of Small Businesses has advised the 170,000 business who it represents to accept the coin after this weekend's deadline.
Barclays said its own customers can continue to deposit their old round pounds into their accounts with it after October 15, but added: "We would recommend that customers allow sufficient time to return old coins rather than leave it until legal tender status is withdrawn". After then, businesses can stop accepting it and they will not be able to give it to you as change.
Poundland also confirmed it will continue to welcome the old coins in more than 850 of its United Kingdom stores until October 31.
THE old one-pound coin is being phased out completely on Sunday (15) but United Kingdom businesses said they have been given too little time to switch to the new one and many are planning to defy the deadline. According to the Guardian, with a week to go, about 500 million coins are still in circulation.
The discount retailer has joined the ranks of Tesco and Poundland in extending its deadline past October 15 when the old pound coins cease to be legal tender.
"This deadline is going to be a challenge given that multiple retailers have made a decision to be more flexible and continue to accept the old £1 coin from shoppers after 15th October", he said.
"After October 15, the 12-sided £1 coin will be the only £1 coin being spent in the UK".
The old pound coins are to be melted down to create new ones.
Prior to the introduction of the coin, which includes new high-tech security features to prevent counterfeiting, one in 30-pound coins we fake. One pound coins were first launched on April 21 1983 to replace £1 notes.
But many institutions across the country may still accept payments with the old coin after the cutoff date, although they will no longer be able to use it when giving change to customers.
The new coin, of which 1.5 billion copies have been made, is "the safest in the world", said Kevin Clancy, director of the Royal Mint Museum.
RBS/NatWest also said it would encourage customers to try to hand in their old coins as soon as possible.