Oh the 6 million dollar question, it depends on how much storage space you have. The main documents to keep would be the assessors report and the decision notice, I would also keep a copy of your original application as a template for when you are next assessed.
I did have one client who celebrated her win by having a bonfire and burning all the unwanted letter. Most documents are usually stored electronically so you do not need to keep paper copies unless you have room and a good filing system.
Gary
Nothing on this board constitutes legal advice - always consult a professional about specific problems
