People have just 100 days left to use the paper £20 and £50 banknotes remaining in circulation, the Bank of England has said.
The last day the notes will have legal tender status is 30 September.
The Bank is encouraging anyone who still has them to use them or deposit them at their bank or a post office before the end of September.
While the majority of paper £20 and £50 banknotes in circulation have been replaced with new polymer versions, there are still more than £6bn of paper £20 notes featuring economist Adam Smith, and more than £8bn of paper £50 banknotes featuring entrepreneur Matthew Boulton and engineer James Watt, in circulation.
That is more than 300m individual £20 banknotes, and 160m paper £50 banknotes.
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It is a year since the Bank first issued the polymer £50 banknote featuring Bletchley Park codebreaker and scientist Alan Turing. The Turing 50 completed the Bank’s “family” of polymer notes, with all of its denominations – 5, 10, 20 and 50 – now printed on polymer.
The Bank of England’s chief cashier, Sarah John, said: “Changing our banknotes from paper to polymer over recent years has been an important development, because it makes them more difficult to counterfeit, and means they are more durable.
“The majority of paper banknotes have now been taken out of circulation, but a significant number remain in the economy, so we’re asking you to check if you have any at home.
“For the next 100 days, these can still be used or deposited at your bank in the normal way.”