Are you sure about "most retailers" as I've never seen that as an option on the websites I've visited (although I've not looked) and your example website is a specialist store.
It is very common just some firms do not make the process very obvious until checkout.
This from Boots, who cannot be considered a specialist store.
'What is VAT exemption and can I claim it?'
Items eligible for VAT relief
Some products that we sell have been specifically designed for use by persons who are disabled or chronically sick. HM Customs and Excise rules allow these items to be purchased by the customer at a VAT exclusive price as long as they are purchased by or for a disabled or chronically sick person. The goods must also be for personal or domestic use only and must be applicable to that person's disability or sickness. These products are shown on our website whether they are eligible for VAT relief.
How do I claim VAT relief for eligible products?
As long as you meet the qualifying criteria (above) the exemption process in the checkout works as follows:
1. Please ensure that you have registered or logged in before placing an order containing an item that you wish to claim VAT relief for.
2. Once you place an item in your basket you will be presented with a 'pop up' which will ask 'will you be claiming the VAT back?' As long as you feel that you meet the criteria above, click on 'yes'.
3. You will then be presented with a page asking you 'who is this product for?' Please click on the appropriate button and then click 'continue'.
4. In order to meet yours and our legal obligations to HM Customs and Excise and in order to avoid paying VAT you will then be presented with a straightforward on-line VAT relief claim form to complete. Please note that we are only able to exempt VAT from the actual goods, but not from the delivery charges (which will attract VAT as normal). After completing the form you will be taken back the normal shopping page and can carry on checking out as normal and you will see the 'VAT saving' as part of your savings total.
5. If you are in any doubt as to whether you are able to claim this relief you should consult notice 701/7 VAT reliefs for disabled people.
What does 'disabled or chronically sick' mean?
A person is 'chronically sick or disabled' if he/she is a person:
- With a physical or mental impairment which has a long term and substantial adverse effect upon his/her ability to carry out everyday activities
- With a condition which the medical profession treats as a chronic sickness, such as diabetes
- With a terminal illness
It does not include a frail elderly person who is otherwise able bodied, or any person who is only temporarily disabled or incapacitated, such as with a broken limb.
Can I claim VAT relief on behalf of someone else?
Yes - but you will be required to put the claimants details on the VAT relief claim form.
Are all products in the 'mobility and daily living aids' subject to VAT relief?
No - only products clearly identified are subject to VAT relief.
Do I have to complete a separate on-line form for every VAT exempt product I order?
No - If you order a number of VAT exempt items on 1 order, you will only need to complete the form once.
How can I find out more about claiming VAT relief?
Please Refer to H M Customs notice 701/7 VAT reliefs for disabled people.