An excess is the amount of the claim you have to pay. If your claim is £1,000 and you have a £100 excess then your insurer will pay £900 and you will pay £100.
What is a compulsory excess?
A compulsory excess means that the policy you have chosen has that amount of excess, you have to pay it if you make a claim. It is very unusual for a policy not to include a compulsory excess although there are certain sections of your policy which will may be exempt i.e. Employers Liability.
What is a voluntary excess?
In return for a lower premium you can opt to include a voluntary excess but of course this will increase the amount you have to pay if you make a claim. If you don’t make a claim, then you have saved money by adding a voluntary excess.