Dualforce

Hi, Hoping that someone can help point me in the right direction whether it be a purchasable module or coding solution. Problem In the UK there is tax relief on certain but not all disability products based on on users health condition. So say if you the customer is severely disabled or has diabetes you pay no Vat/Tax on certain products whereas everybody else must pay the price plus Vat/Tax. I need to apply a tax exemption to certain products for certain customers. I would like not to have to create duplicate items with different prices as this becomes confusing for the customer. But think the answer must lie in and around specific pricing for user groups. But am unable to get my head round a full solution I have searched the forums but struggling to find anybody that has mentioned or solved this Issue. As always guidance and advice appreciated. Jon PS 1.5.6