Dual Fuel Tariffs: One Supplier for Gas and Electricity

A dual fuel tariff is a single energy contract that covers both the gas and the electricity a home uses, with one supplier and one bill. Instead of paying one company for electricity and another for gas, the household receives one monthly or quarterly invoice covering both fuels¹. Pretty much all energy suppliers offer dual fuel tariffs, because they are cheaper and easier to manage for the supplier as well as the customer¹. Whether a supplier offers one at all is up to them, and it can differ from supplier to supplier, but most do².

The attraction is partly convenience and partly price. Most suppliers offer a discount on dual fuel tariffs that makes them cheaper than buying separate gas-only and electricity-only tariffs³. But the saving is not guaranteed: there is no assurance that a dual fuel deal beats every combination of separate tariffs, and the size of the discount has historically been modest, a matter of pounds a year rather than hundreds. This page explains what the discount actually is, which homes cannot get dual fuel at all, what happens to the bills and meters, and how the price cap and typical consumption values determine what a dual fuel household actually pays.

One contract, one supplier, one bill

A dual fuel tariff covers both gas and electricity use, and the household is billed for both with one monthly or quarterly invoice¹. That single bill is the defining feature. Everything else about the tariff, whether the rates are fixed or variable, how the standing charges are set, what the exit terms are, works in the same way as it would on separate contracts, only combined.

For a household already on two separate single-fuel tariffs, one for gas and one for electricity, switching to a dual fuel tariff is straightforward². The switch itself is administrative rather than physical: there is no downtime between the old contract ending and the new one beginning, and no supplier visit is needed unless a smart meter is being installed at the same time¹. The gas keeps flowing and the electricity keeps flowing throughout.

It is worth being clear about what does not change. A dual fuel tariff does not alter the physical supply of either fuel, does not change the meters, and does not merge the two fuels into a single unit rate. Gas and electricity are still metered, priced and charged separately within the one bill. What the household gains is one supplier relationship, one direct debit, one customer service contact point and, usually, one discount for having both fuels with the same company. For a fuller map of how this fits among the UK's tariff types generally, see the guide to UK energy tariffs.

How the combined gas and electricity discount works

The dual fuel discount is a reduction a supplier gives for taking both fuels from it. Most suppliers offer one, and the discount is what tends to make dual fuel tariffs cheaper than buying gas-only and electricity-only tariffs separately³. The discount can show up in different places: cheaper unit rates, lower standing charges, or occasionally cashback, but the effect is the same, a small reduction in the annual cost of having both fuels with one supplier.

The size of the discount has always been modest, and the official record shows how modest. When Ofgem examined the market, the average dual fuel discount for a typical direct debit customer on a standard tariff with one of the major suppliers was 1% (£13), and for a quarterly cash or cheque customer it was 0.7% (£9)⁴. Going further back, British Gas Trading offered a yearly discount of £14.50 for dual fuel customers in 2001⁷. These are small sums against a typical annual bill that now runs to four figures.

That rule matters for anyone comparing deals. Because discounts must be shown as a pounds-per-year figure with the same terms as the single fuel equivalent, the discount is visible and comparable rather than buried in the unit rates. A household weighing a dual fuel deal against two separate tariffs can see exactly what the combined deal is worth in cash terms over a year, and can weigh that against any difference in the unit rates and standing charges on offer. The comparison is not always straightforward, and the page on comparing energy tariffs covers how annual cost projections are built.

Do combined tariffs cost less than single fuel deals?

There is no guarantee that a dual fuel deal is cheaper than separate gas and electricity tariffs¹. That is the honest starting point, and it is worth holding onto when a comparison site or a supplier advertises a dual fuel discount as if it were a large saving. What can be said is that suppliers tend to pass on some of the savings from having one customer for both fuels, and most suppliers price their dual fuel deals so that they beat their own separate tariffs³.

The comparison that actually matters is not dual fuel against the same supplier's separate tariffs, but dual fuel against the best separate tariffs available across the whole market. The cheapest gas-only deal from one supplier plus the cheapest electricity-only deal from another can, in some conditions, beat a dual fuel deal with a discount attached. Whether it does depends on the unit rates and standing charges on each side, and those change with every price cap review and every round of product launches. The dedicated comparison of dual fuel versus separate tariffs works through this in detail.

One relationship within the dual fuel category itself is more consistent: a standard variable dual fuel tariff will cost more than a fixed dual fuel tariff most of the time². So the bigger financial decision for most households is not usually dual fuel versus separate, but fixed versus variable within whichever structure they choose. A household that fixes both fuels separately with two suppliers may still do better than one that sits on a dual fuel standard variable tariff, which is why the discount alone should never be the reason for choosing a deal.

Fixed or variable: which structure sits underneath

A dual fuel tariff is a billing structure, not a pricing structure. Underneath it sits one of the main tariff types, and Ofgem sets out that there are 3 main types: fixed rate, standard variable tariff (SVT) and multi-rate tariff⁹. A dual fuel deal can be fixed, variable, or in some cases built around multi-rate electricity metering, and the choice among these matters more for the bill than the choice between dual fuel and separate contracts.

On a variable rate dual fuel tariff, the rate paid changes depending on the wholesale, or industry, price of energy¹. That means bills rise and fall as the market moves, with the default tariff cap setting the ceiling for households on standard variable and default tariffs¹⁰. On a fixed rate dual fuel tariff, the household is locked into a plan for a set period at a fixed amount per unit of energy¹. Consumer research for Ofgem tested the options households actually face: a 12 months fixed term, a 24 months fixed term, and a standard variable tariff¹¹.

The Welsh Government's energy advice, drawing on consumer guidance, recommends fixing for no longer than 12 months¹². That reflects the trade-off at the heart of the fixed versus variable choice: a longer fix buys more certainty but locks in today's rates for longer, and a shorter fix keeps the option to move if the market falls. The pages on fixed-rate energy tariffs and the fixed versus variable comparison cover the mechanics of each.

Homes that cannot get dual fuel

Not every home can have a dual fuel tariff, because the tariff needs both fuels supplied to the property. Single fuel tariffs exist for people with either gas-only or electricity-only premises². An all-electric home, whether it uses storage heaters, panel heaters or a heat pump, has no gas supply to put on the contract, so dual fuel is simply not available to it. The same applies to a home with gas but no electricity supply, which is rare but not unknown.

The larger group is homes off the gas grid. Around them sits a different energy world: oil, LPG, solid fuel and electricity. Government statistics describe the Home Upgrade Grants programme as having provided energy efficiency upgrades and low carbon heating to low income households in properties which are off the gas grid and in energy efficiency bands D to G¹³. A home heated by oil or LPG buys its fuel from a heating oil distributor or an LPG supplier, not from a domestic energy supplier, so there is no gas contract to combine with an electricity contract.

Support schemes recognise this split. The Alternative Fuel Payment Alternative Fund was designed for households who use alternative fuels with no direct energy supplier, for example those living in park homes¹⁴. In Northern Ireland, where many homes are off the gas network, the home heating oil support scheme exists precisely because oil buying sits outside the domestic energy supplier market¹⁵. For these households, the electricity tariff is the only switchable contract, and the relevant choices are among electricity-only deals, covered in the guide to which tariffs your meter and home allow.

There is one partial route worth knowing about. Several suppliers offer green gas tariffs without requiring the household to sign up for electricity or dual fuel³. That is a gas-only product with a renewable element, and it shows that the single fuel side of the market remains active for homes that cannot or do not want to combine fuels.

Bills, admin and smart meters: what a dual fuel tariff means day to day

Day to day, a dual fuel tariff means one bill, one direct debit and one supplier to deal with when something goes wrong. The switch itself is light on administration: there is no paperwork to complete and send off, except for giving the old supplier an up-to-date meter reading so they can produce an accurate final bill¹. There is no downtime between the old contract ending and the new one beginning, and no supplier visit is needed unless a smart meter is being installed¹.

Smart meters change what a dual fuel household can access. With a smart meter, a household can access more flexible tariffs, including dual-rate tariffs¹⁶. That matters because the more innovative tariff products, the time-of-use deals, the EV rates, the flexible pricing, generally require one. The Committee of Public Accounts noted that some innovative energy suppliers were able to offer tariffs, to consumers with smart meters, that could save up to two-thirds of the costs of charging electric vehicles if charging at certain times of day¹⁸.

One limit on the tariff side is worth stating plainly. Except by switching, a household does not control the tariff its energy supplier sets¹⁹. The supplier chooses the rates, the standing charges and the products on offer; the household's power lies in choosing among them, and in choosing how much energy it uses. That is the practical case for understanding the market rather than treating the tariff as fixed background: the tariff is the single biggest lever on a dual fuel bill that the household can actually pull.

Consumer research also shows how much confusion surrounds tariff status. In Ofgem's research, considerably more consumers claimed to be on fixed tariffs (38%) than the official data suggests (11%)¹¹. Among those who say they are on a fixed tariff for electricity, 55% report being very confident that is the case, while 38% say they are only somewhat confident¹¹. A household that checks its bill, confirms what it is on, and knows when its fixed term ends is ahead of most of the market.

Leaving charges and the 49 day rule for switching

Leaving a fixed term dual fuel tariff early means paying an exit fee for both types of energy, gas and electricity¹. That is a point specific to dual fuel worth noting: the penalty applies to each fuel, so the cost of leaving early is the combined exit fee rather than a single charge.

The escape hatch is the switching window at the end of the contract. The exit fee is waived when the household enters the final 49 days of the contract³. From that point, the household can arrange a new deal, with the same supplier or a different one, without paying anything to leave. The 49-day window exists so that a fixed tariff can roll into a new deal rather than drifting onto the supplier's standard variable rate when the term ends.

The practical sequence is simple:

1. Note the end date of the fixed term when the tariff starts.
2. From 49 days before that date, compare deals without any exit fee applying³.
3. Arrange the new tariff before the old one ends, so there is no gap on a variable rate.
4. Give the old supplier a final meter reading for the closing bill¹.

The fuller rules on exit fees, when they apply and how they are capped, are covered in the guide to exit fees and energy tariff contract terms.

Fixed dual fuel deals: the term, the protection and the limits

A fixed rate dual fuel tariff locks the household into a plan for a set period at a fixed amount per unit of energy, usually 12 months¹. The protection is on the unit rate: the price per kWh of gas and electricity does not move during the term, whatever the wholesale market does. The standing charge is set at the start of the term as well, so the bill varies only with how much energy the home uses.

The terms on the market cluster around one and two years. Ofgem's consumer research tested a 12 months fixed term, a 24 months fixed term and a standard variable tariff as the realistic options households weigh¹¹. Welsh Government guidance recommends fixing for no longer than 12 months¹², which reflects the main limit of a longer fix: it trades flexibility for certainty, and a household locked into a 24-month deal at a high point in the market waits a long time for the chance to move without a penalty.

The other limits are worth naming. A fixed rate fixes the price, not the bill: a cold winter means more kWh and a higher bill even on a fixed tariff. And leaving early costs money, with the exit fee charged on both fuels¹, unless the household is inside the 49-day window³. What a fix delivers is predictability of the rate, and for many households that is worth having, but it is not a guarantee of the lowest cost over the whole term. The question of whether to fix and what happens when a fixed deal ends are covered in their own pages.

How the price cap and typical consumption values shape the bill

The price cap is the backdrop to every dual fuel bill. It protects households on standard variable and default tariffs¹⁰. For a dual fuel household on a variable tariff, the cap sets the maximum unit rates and standing charges the supplier can charge; for a household on a fixed tariff, the cap is the benchmark against which the fixed deal is judged.

The headline figures are built on typical consumption. Previous price cap figures were based on 12,000 kWh of gas and 2,900 kWh of electricity a year for a typical dual fuel household⁶. That assumption is what turns a set of unit rates and standing charges into a single annual bill figure, and it is why the same cap produces different bills in different homes. A household using half the typical gas will pay well under the headline, and one using more will pay over it.

The cap level itself moves every quarter. For 1 July to 30 September 2025 the cap for a direct debit dual fuel customer was £1,849²⁰. For January to March 2026, the cap made an energy bill for a dual fuel home with typical usage in Great Britain paying by direct debit around £1,758⁵. Another official figure for the same period puts it around £1,641, and the two differ⁵. Welsh Government guidance notes that even for January to March 2026, the annual dual fuel energy bill for a typical home is over £500 more than in winter 2020 to 2021⁵.

Standing charges are the part of the cap a household pays regardless of use. Policy and network costs within the nil consumption level of the price cap, the amount a dual fuel customer pays for no energy at all, are around £150 for a GB average dual fuel customer²¹. Ofgem has been consulting on going further, for example requiring suppliers to offer tariffs that represent a £200 discount from the nil consumption dual fuel cap level²².

Historical context explains how large the numbers became. Under the Energy Price Guarantee, the typical annual dual fuel bill was around £2,500 per year in Great Britain and around £2,109 per year in Northern Ireland²³. The cap's regional detail runs deep: even the nil consumption charge varies by region and meter type, with the electricity element at £193.01 for a multi-register metering arrangement in the Eastern region for 1 April to 30 June 2024²⁴.

For a household thinking about energy independence, the price cap is a reminder of the dependence that remains in any tariff. A dual fuel household buys both its fuels from a supplier, at rates shaped by a regulator, on a grid and a gas network it does not control. The tariff choices available, fixed, variable, dual fuel, single fuel, determine how that dependence is priced, not whether it exists. The one lever the household fully controls is how much energy it uses¹⁹, and the choices that reduce that, insulation, efficiency, and generation of its own, are the ones that shrink the bill whatever the cap does next.