New £20 note enters circulation – here's what you need to know

The polymer notes replace the old paper twenties, which have been in circulation since 2007 and feature economist Adam Smith – though you'll still be able to use the paper £20 notes in the months to come. 

The latest £20 note has been described as "the most secure Bank of England banknote yet", with two 'windows' and a two-colour foil to make it tough to counterfeit. 

It's the third plastic banknote to be issued, following the Winston Churchill £5 note and the Jane Austen £10 note. A new plastic £50 note will be released in 2021, featuring scientist Alan Turing. 

The new £20 notes will make their way into consumers' pockets over the next few weeks, with the Bank of England saying that half of all ATMs across the UK are expected to be dispensing them within two weeks. 

If you can't wait to get your hands on one, they're also available to exchange for paper £20s from the Bank of England counter as of today.

What does the new £20 note look like? 

The new £20 note (pictured above) features a self-portrait of JMW Turner, as well as one of his most celebrated paintings, The Fighting Temeraire, voted the nation's favourite painting in a 2005 poll. 

It also shows Turner's signature from his will, in which he left many paintings to the nation, and a quote reading "light is therefore colour". 

The note also has various security features to help combat forgeries, including: 

• Two windows. The larger one is based on the shape of the fountains in Trafalgar Square, and has a blue and gold foil showing Margate Lighthouse and the Turner Contemporary art gallery. The smaller one is found in the bottom corner of the note and is inspired by Tintern Abbey, which Turner painted. 

• A hologram which changes between the words "Twenty" and "Pounds" when the note is tilted.

• The Queen's portrait in a window, with the words "£20 Bank of England" printed twice around the edge.

• Two foil patches – a silver one with a 3D image of the coronation crown, and a purple one containing the letter T, which is based on the staircase at the Tate Britain art gallery.

When are the old paper £20 notes being phased out?

There are over two billion £20 notes in circulation – but don't worry, you can carry on spending your paper twenties as normal for the time being. 

They will eventually stop being legal tender, but the Bank of England says it will give six months' notice before this. 

Even after the notes stop being legal tender, banknotes officially hold their face value "for all time". So if you do find a paper £20 note stuffed down the back of the sofa after they're withdrawn, you'll be able to exchange it with the Bank of England in London, in person or by post (at your own risk).

What's more, many banks and building societies will often accept old notes from their own customers after they are withdrawn, and the Post Office may accept withdrawn notes as deposits into a bank account you can access through the Post Office.

How can I spot a rare, valuable £20 note? 

When the new £5 note was released in 2016 some rare new notes started selling for £100s on eBay – see MSE Jenny's How to check if your new fiver's worth £100s blog for more.

Now the new £20 note's been released, it's again expected that some with special serial numbers could be worth a lot more than others.

Serial numbers on the notes feature two letters, followed by eight digits. Money-specialist website ChangeChecker.org says the following numbers are the ones collectors are looking out for:

• Serial numbers 23 041775 and 19 121851, representing the dates of JMW Turner's birth and death. 

• Serial number 17 751851, representing Turner's birth and death years combined. 

• Serial number 18 381839, representing the respective years that The Fighting Temeraire was painted and exhibited at the Royal Academy.

• Consecutively numbered notes – eg, if you have multiple AA01 notes – and novelty numbers such as 007. 

Not all the notes produced by the Bank of England will be circulated, though. For example, when the Winston Churchill £5 note was released, the Queen was given the note with the lowest serial number – AA01 000001 – while the note numbered AA01 001945 was donated to the Churchill War Rooms.