People are being urged to check if they have any United Kingdom paper £20 or £50 notes before they are withdrawn from circulation.
They will be withdrawn on September 30, 2022.
Anyone with notes should pay them in to their bank or have them exchanged for newer notes, says the government.
They may also be spent while they remain legal tender, although acceptance would be at the discretion of the business owner.
The withdrawal from circulation follows the introduction of polymer, or plastic, versions of both notes which include additional security features designed to make them harder to counterfeit.
The £20 note was introduced in February 2020 and features a picture of the artist JMW Turner, and the £50 note was introduced in June 2021 and features the mathematician and computer scientist Alan Turing.
Isle of Man Bank will continue to accept the discontinued notes after the deadline and send them back to the UK.
Most other banks in the island are expected to take a similar approach.
Further information about the withdrawal of the paper UK £20 and £50 notes is available via the Bank of England website.