The Bank of England has issued an update amid plans to scrap old paper £20 and £50 notes featuring the Queen later this month.
Anyone still using paper £20 and £50 notes have just over one week until they will no longer be able to purchase goods with their money.
September 30 is the last day that the Bank’s paper £20 and £50 banknotes will have legal tender status.
It 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.
They will be replaced by polymer notes which have been introduced to help boost security and stop fraud.
A Bank of England statement said: "The Bank of England Counter is currently open from 9.30am to 3pm Monday to Friday and is experiencing very high demand. There will be long queues and you may encounter waiting times in excess of an hour.
"We would ask that you kindly consider the long wait times when travelling to the Bank to undertake an in person exchange - if you arrive after 2pm it is possible you may not get served before we close. Unless you require your banknotes immediately, we would suggest sending your banknotes via the post."
As well as banks, Brits will also be able to exchange the old notes on Post Offices too.
The Bank of England’s chief cashier Sarah John said in June: “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.”
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