The Bank of England has said that at least £2.1bn worth of old £10 notes need to be spent or exchanged before they cease to be legal tender on 1 March.
From next month the new plastic polymer tenners will officially replace the old £10 notes, after entering circulation in September last year.
Returns of the paper £10 notes are averaging £85m or 8.5 million notes a week, according to the Bank of England.
To exchange the old notes after the deadline, retailers can either post the notes to the Bank of England, or visit the Bank in person in the City of London. The Bank will exchange all old £10 notes indefinitely.
In the meantime, local banks, post offices and other retailers will exchange the old £10 notes. However, they are not legally required to accept old notes after the deadline.