Millions of households only have six months left to use up any everyday stamps before they become worthless.
Royal Mail is phasing out so-called "definitive" stamps - ones that feature the Queen's head - by the end of January 2023.
After this date, you can only use barcoded stamps with the Queen’s profile on, or non-barcoded Christmas or special collection stamps.
If you try to send mail using the old stamps beyond the deadline, you may face an extra charge.
Sending a letter without postage currently incurs a £2 charge, according to the Royal Mail website.
An exchange system is now in place for those who don’t think they will be able to use the stamps before the cut off point.
Royal Mail’s "Swap Out" scheme lets you exchange the stamps for free by completing a form.
You need to use a standard form for stamps worth up to £200, or a bulk stamp form for stamps worth more than £200.
You cannot take the stamps to the Post Office to be swapped.
Both forms are available on the Royal Mail website where they can be printed and filled out.
For those who don’t have access to a printer, you can request that the documents are posted to you by filling in this form here.
Alternatively, to request the form is delivered to you, you can call customer services on 03457 740740.
The standard form is also available to collect in person at your local delivery office, whereas the bulk form is only found using the above options.
If you have collected the form or had it sent to you, it will come with a freepost envelope for you to send the form off with the stamps for free.
For those who have printed the form themselves, you’ll need to send the envelope to "Freepost Swap Out" - no other address details are needed and it’ll be free of charge.
Royal Mail advises those sending bulk forms to send via special delivery.
The additional cost of doing this will be refunded by Royal Mail in the form of barcoded stamps worth the same amount.
The exchange should take place within seven working days.
If you have not received the new barcoded stamps within two weeks, you are advised to call customer services on the above number.
Nick Landon, Royal Mail chief commercial officer, said earlier this year: "Please check your kitchen drawers, wallets and purses for older non-barcoded stamps and make sure you use them up by 31 January 2023."
