An excess payment, also known as a deductible, is the fixed contribution you must pay each time the car is repaired through the car insurance policy. Normally the payment is made directly to the accident repair "garage" (the term "garage" refers to an establishment where vehicles are serviced and repaired) when you collect the car. If one's car is declared to be a "write off" or "total loss"("write off" is commonly used in motor insurance to describe a vehicle the worth of which is less than the cost of repair), the insurance company will deduct the excess agreed on the policy from the settlement payment it makes to you.
If the accident was the other driver's fault, and this is accepted by the third party's insurer, you'll be able to reclaim your excess payment from the other person's insurance company.
Compulsory excess/deductible
A compulsory excess is the minimum excess payment the insurer will accept on the insurance policy. Minimum excesses vary according to the personal details, driving record and insurance company.
Voluntary excess/deductible
To reduce the insurance premium, the insured may offer to pay a higher excess than the compulsory excess demanded by the insurance company. The voluntary excess is the extra amount over and above the compulsory excess that you agree to pay in the event of a claim on the policy. As a bigger excess reduces the financial risk carried by the insurer, the insurer is able to offer you a significantly lower premium.