UP to 13m households, or about half of all energy customers, have never switched suppliers and could save an average £200 — and in some cases as much as £500 — according to comparison firm Energyhelpline.

The energy giants penalise loyal customers who pay by cheque or cash, have separate suppliers for gas and energy and don’t manage their accounts online, so this is where you can make the biggest savings.

However, if you prefer to pay by cheque — as many of us do — you could still cut your bill by hundreds of pounds.

1 CHOOSE DUAL FUEL

If you have never switched, you are likely to be with British Gas for gas and a local supplier for electricity. In London, the standard annual gas bill with British Gas is £894 while EDF, the supplier for Londoners who have never switched, charges £469 for electricity — a total of £1,363.

If the customer switched to EDF for gas and electricity, however, the annual bill would fall to £1,230 — a saving of £133.

Savings depend on your region and range from £297 in southern England to £121 in the southwest. They also depend on usage, so use a comparison site such as Uswitch.com before you transfer.

2 GO TO DIRECT DEBIT

Rather than wait for energy firms or the government to reduce the costs of paying by cheque or cash, you could make an additional saving of over £42 a year by switching to direct debit payments, bringing your average bill to £1,188 a year with EDF in the above example.

The cheapest direct debit standard plan, on average, is offered by Scottish and Southern (SSE) with a rate of £952 a year — £54 less than it charges standard credit customers.

However, if you don’t want to go to direct debit, the cheapest plan for cash or cheques is from SSE too at £1,006.

Tim Wolfenden at Uswitch said: “Not everyone wants to pay by direct debit. Many prefer to keep their cash as long as possible rather than let the energy giants earn interest on it. It’s still worth checking you’re on the best tariff, though.”