Royal Mail is urging people to use stamps without a barcode by January 31 2023, when they cease to be valid.

The change affects ordinary stamps featuring Queen Elizabeth II, which must be used before the deadline exactly 100 days from Monday.

The barcoded stamps will continue to feature an image of the late Queen.

The postal service previously launched a stamp swap scheme for people to exchange their old stamps for new ones.

Special stamps with pictures on and Christmas stamps without a barcode will continue to be valid and don’t need to be swapped out.

The barcoded stamps were introduced in February as part of a move to modernise the service, and to allow enhanced security features, Royal Mail said.

It also said barcodes will “enable exciting new services by connecting physical stamps to the digital world”, such as exclusive videos available by scanning the codes in an app.

To exchange, people must send their non barcoded stamps to Royal Mail, along with an exchange form which can be printed or requested via an online form.