<p>Suppliers must operate under the regulatory framework set by Ofgem. Ofgem is in the</p><p><?notus-xml column=436?></p><p>process of introducing new rules to simplify tariffs through their retail market reforms, including standardising the way discounts are applied.</p><p>Under Ofgem's rules suppliers will be limited to four core tariffs per fuel. Suppliers will be allowed to vary the cost of the tariff depending on the payment method used by the customer, provided that the differential between payment methods is cost reflective.</p><p>As direct debit customers cost less to serve than customers who pay on receipt of bill and customers who have pre-payment meters, we would expect direct debit customers to continue to benefit from lower charges.</p>