Yes they can alter it every year at renewal - unless the policy said when you took it out that this was the terms for life (which would be unlikely in my experience). My cats' insurance changes every year as they get older, the excess and percentage contribution increases. Shop around - I have mine with PetPlan at the moment, the advantage with that one is that they pay for life if the animal develops a medical condition, whereas some of the others will only pay for a year. My cat has kidney disease which developed last year so it is reassuring for me to know that they will pay his bills for the rest of his life (after the excess, of course!).