The notes will no longer be legal tender after 30 September 2022, which is exactly one year after the polymer £50 note featuring scientist Alan Turing was released
While the majority have been replaced with the newer versions, there are still more than £6bn worth of paper £20 notes in circulation, featuring economist Adam Smith.
There are also more than £8bn worth of paper £50 notes still being used in the UK economy, which show engineers Boulton and Watt.
This means in total, there are over 300m individual £20 bank notes and 160m paper £50 notes.
Speaking ahead of the date, Bank of England chief cashier Sarah John said: “Changing our bank notes 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 bank notes have now been taken out of circulation but a significant number remain in the economy.
“For the next 100 days, these can still be used or deposited at your bank at the normal way.”
Paper £20 notes started being withdrawn on 20 February 2020, which was when the polymer version entered circulation. Paper £50 notes started to be withdrawn on 23 June 2021, when the polymer note was released.
All polymer notes have two key security features – a hologram that changes image and see-through windows.
The polymer £5 note was the first to change from paper, which was issued on 12 September 2016 and features Sir Winston Churchill. The £10 note followed this in September 2017 and features Jane Austen.
The latest edition of the £50 note means all Bank of England banknotes are now available on polymer.