We will withdraw legal-tender status of paper £20 and £50 notes after 30th SEPTEMBER. If you have any, we encourage you to use them, or deposit them with your bank or Post Office, before then.
[The Series F paper banknotes being withdrawn feature economist Adam Smith on the purple £20 notes; and steam-engine industrialists Matthew Boulton and James Watt on the red £50 notes. These are the same colours as the Series G polymer notes that replace them.]
As paper notes are returned to the Bank of England, they are being replaced with the newer polymer £20 notes featuring the artist JMW Turner, and £50 notes the computer pioneer Alan Turing. After 30th September, only our polymer notes will have legal tender status.
You can read further guidance at
https://www.bankofengland.co.uk/banknotes/paper-20-paper-50-withdrawal