You can switch energy suppliers whenever you wish, although if you are on a fixed price tariff you may have to pay an exit fee depending on how far into your current deal you are. Different suppliers will have different rules, so it’s important to check with your current energy supplier to see how much you could be charged for ending your deal. Suppliers must tell you at least 42 days before your end date that your current deal is about to expire, so this is a good time to switch. If you let your fixed tariff deal end without switching, you will be rolled onto your supplier’s standard variable tariff, which will usually be one of their most expensive deals.