Those who have an age, health or disability reason for not wearing a face covering should not be routinely asked to give any written evidence of this, this includes exemption cards. No person needs to seek advice or request a letter from a medical professional about their reason for not wearing a face covering.
You can use this card from The Welsh Government to show that you are exempt from wearing a face covering. This is a personal choice and is not necessary in law. Some people may feel more comfortable showing something that says they do not have to wear a face covering.
Download the exemption card here: