Start With Your Own Numbers, Not the Headline Rate

Before you look at a single tariff, dig out your last year of bills or your annual statement. What you need is your actual usage in kilowatt hours (kWh) — one figure for electricity, one for gas. Suppliers publish estimates based on the "typical household", but typical is a blunt instrument. A well-insulated flat with two occupants and a heat pump can use less than half the gas of a draughty four-bedroom semi with a family of five.

If you have smart meters, your in-home display or supplier app will show your usage history. If not, take a meter reading today and again in a week, then scale it up across the year. It won't be perfect through the seasons, but it will be far closer to reality than a national average. Having those two figures in front of you turns tariff comparison from guesswork into arithmetic.

Fixed, Variable and How Long You're Tied In

A fixed tariff locks your unit rates and standing charge for a set period, usually 12 or 24 months. You get certainty: your bill still rises and falls with how much you use, but the price per kWh won't move. A variable tariff tracks the market, so it can fall as well as rise — and it can rise sharply.

Ask directly: how long does this contract run, and what happens at the end? Some fixed deals roll onto a standard variable rate when they finish, which is often considerably more expensive. Others will contact you before the end date with renewal options. Diarise the end date the day you switch, and set a reminder a month before. That single habit saves more money than most people realise.

Exit Fees: The Question Nobody Asks

Exit fees are the charge for leaving a fixed contract early, and they vary enormously. Some tariffs have none at all; others charge a flat fee per fuel, so a dual-fuel deal could cost you twice over. Before signing, ask:

• Is there an exit fee, and how much is it per fuel?
• Does it apply if I move house, or only if I change supplier?
• Is there a window near the end of the contract when I can leave without charge?

Variable tariffs normally carry no exit fees, which is part of their appeal — you keep the freedom to jump to a better deal. If you're likely to move home during the contract term, that flexibility matters more than a slightly lower unit rate.

Unit Rates and Standing Charges Explained Simply

Your bill has two moving parts. The unit rate is what you pay for each kWh you use. The standing charge is a fixed daily amount, paid whether you use any energy or not, covering things like meter maintenance and network costs.

This matters because a tariff with a low unit rate can still be a poor deal if it carries a high standing charge. Run the sums against your own usage: multiply your annual kWh by the unit rate, add the standing charge multiplied by 365, and compare the totals. Comparison tools will do this for you, but knowing the arithmetic yourself means you can spot a deal that looks cheap and isn't.

Remember too that standing charges vary by region and by how you pay. Direct debit is usually cheapest; prepayment and quarterly billing tend to cost more.

Does the Tariff Match the Way You Actually Live?

Some tariffs reward particular habits. If you charge an electric car overnight, run a heat pump, or use storage heaters, a time-of-use tariff with cheaper off-peak rates can cut your costs significantly — but only if you genuinely shift your usage into those hours.

Be honest with yourself. If your household runs the washing machine at seven in the evening and the heating comes on at six, an off-peak tariff may cost you more, not less. Ask:

• Which hours are cheapest, and can I realistically use them?
• Is a smart meter required, and do I already have one fitted?
• What happens to my bill if most of my energy use stays at peak times?

Your Checklist Before You Sign

Work through this before you click confirm:

• Usage: your own annual kWh figures for gas and electricity
• Contract length: start date, end date, and what follows
• Exit fees: the amount, per fuel, and any exceptions
• Unit rate and standing charge: checked against your real usage
• Payment method: any direct debit discount, and whether it's a condition
• Smart meter: required, compatible, or not needed at all
• Cooling-off period: usually 14 days, so read the terms properly within that window

Switching isn't complicated once you know what to look for, and the questions above take twenty minutes to work through. Do that, and you'll sign with confidence rather than hope — which is exactly how it should feel.