A rolling contract (sometimes also called an evergreen contract) is one that carries on until you cancel it. During the period of the contract, the price of electricity can go up or down in accordance with the terms of the contract. You can end this type of contract at any time on 28 days notice if you are moving to another supplier, or 2 days notice if you are moving house. There is rarely any cancellation fee. Rolling contracts may contain periods during which the supplier guarantees not to increase prices. If you cancel during one of these periods you may be liable for a cancellation fee.