Cheapest Energy Supplier UK: Every Active Provider and How Prices Compare (2026)

How many energy suppliers are active in the UK right now

Ofgem's retail market indicators recorded 17 active domestic energy suppliers as of September 2025: 16 supplying both gas and electricity and one supplying electricity only. This is a far smaller market than it was before the 2021 to 2022 energy crisis, when dozens of smaller suppliers exited or were placed into the Supplier of Last Resort process. Ofgem's most recent state of the market report also notes that six large suppliers hold around 91 percent of the domestic market between them, meaning most switching activity happens between a small number of established names and a longer tail of smaller independents.

Every active UK domestic energy supplier

The table below lists major active suppliers confirmed through Citizens Advice's statutory quarterly star rating, which only covers suppliers with more than 25,000 customer accounts, alongside Ofgem's market data. Citizens Advice holds a statutory duty to publish this performance information, distinct from private comparison sites.

This is not a ranking. The order above follows legacy versus independent status, not price or quality. Ofgem's full count of 17 active suppliers means a small number of smaller independents are not individually listed here; check Ofgem's retail market indicators for the complete current count before assuming this table is exhaustive.

How the energy price cap actually works

The price cap does not limit your total bill. It limits what a supplier can charge per unit of gas and electricity, and the daily standing charge, for customers on a standard variable tariff. From 1 July to 30 September 2026, a dual-fuel direct debit customer on the cap pays on average 26.11 pence per kilowatt hour for electricity and 7.33 pence per kilowatt hour for gas, with standing charges of 57.19 pence a day for electricity and 29.04 pence a day for gas. Your actual bill still depends on how much energy your household uses. Customers on a fixed-rate tariff are not affected by the cap changing, since their price was agreed for the length of the fixed term.

Fixed versus variable tariffs

A standard variable tariff moves with the price cap every three months, in January, April, July and October. A fixed tariff locks in a rate for an agreed term, typically 12 months, and does not change even if the cap rises or falls during that period. Ofgem's own market data shows the price cap has moved in both directions across recent quarters, which is why some households on fixed deals end up paying more than the cap and others end up paying less, depending purely on timing rather than which supplier they chose.

What actually determines whether a tariff is cheap

• Payment method. Direct debit tariffs are typically cheaper than standard credit (paying on receipt of a bill) or prepayment, because suppliers face lower costs and risk collecting by direct debit.
• Meter type. Prepayment meter customers are covered by a separate cap level to direct debit customers, and older prepayment meters may not access the newest tariffs at all.
• Region. Unit rates and standing charges vary by region, since network costs differ across the country, so the same tariff type can cost a different amount in Scotland compared with the South West.
• Smart meter access. Some of the lowest-cost tariffs, including time-of-use and weekend discount tariffs, require a working smart meter to access.
• Dual fuel versus single fuel. Buying gas and electricity from the same supplier sometimes carries a dual-fuel discount, though this varies by supplier and is not universal.

How to switch energy supplier

Ofgem's own guidance states switching should take up to 5 working days once it starts, with a 14-day cooling-off period built in before that. You do not need to contact your old supplier directly at any point in the process.

1. Compare your current rate against published tariffs. Check your current unit rate and standing charge against what is currently available, using your postcode and payment method for an accurate comparison.
2. Sign up with the new supplier. This starts your 14-day cooling-off period. Your contract only goes live if you do not cancel within that window.
3. The new supplier contacts your old supplier. They coordinate the switchover date between themselves so your supply is never interrupted.
4. The switch completes within 5 working days once it formally starts, under Ofgem's standard. You can ask for a later date if you prefer.
5. Provide an opening meter reading on the switch date if you can, to help both suppliers produce accurate final and opening bills.
6. Your old supplier sends a final bill within 6 weeks and refunds any credit balance you are owed.

You can switch supplier at any point on a standard variable tariff without an exit fee. If you are on a fixed-term tariff, you can usually switch inside the final 49 days of the contract without paying an exit fee, since Ofgem's rules do not allow suppliers to charge one in that window.

Should you fix your tariff or stay on the price cap

A standard variable tariff moves with the price cap every three months. A fixed tariff locks in a rate, typically for 12 months, regardless of what happens to the cap during that period. Neither option is factually "cheaper" in every circumstance: it depends on which direction the cap moves after you decide.

Forecasters including Cornwall Insight have pointed to a modest fall in the cap for the October to December 2026 period after the 13 percent rise in July, though any forecast of a future cap remains a prediction rather than a confirmed figure, since Ofgem only sets the cap three months at a time based on wholesale costs at that point. A fixed tariff removes that uncertainty entirely in exchange for giving up any benefit if the cap falls. A variable tariff keeps that possible upside, at the cost of also being exposed if the cap rises again.

How to compare suppliers on factual terms

Rather than a single "cheapest supplier" answer, a factual comparison rests on a small number of published figures: the unit rate and standing charge for your region and payment method, whether the tariff is fixed or variable and for how long, any exit fees, and the supplier's Citizens Advice star rating for service quality. These figures are published by suppliers and by Ofgem, and none of them require a lead form or a phone call to obtain.

Is Octopus Energy the cheapest supplier?

Octopus Energy is the largest UK electricity supplier by customer numbers, but size does not determine price. Its standard variable tariff is capped at the same level as every other supplier's, and its fixed and time-of-use tariffs are priced independently and change over time, so cheapness has to be checked against current published rates rather than assumed from market share.

Why do some suppliers cost less than the price cap?

The price cap sets a ceiling for standard variable tariffs, not a fixed price. Suppliers can and do offer fixed tariffs priced below the cap when they expect wholesale costs to fall, which is why the cheapest tariff basket in the market can sit below the average cap figure at any given time.

Does switching supplier always save money?

Not automatically. If you are already on a competitively priced fixed tariff, switching before it ends can mean paying an exit fee and moving to a less favourable rate. Comparing your current rate against current published tariffs, rather than switching by default, is the only way to know if a move actually saves money.

How many UK energy suppliers have failed since the energy crisis?

Multiple suppliers exited the market or were moved into Ofgem's Supplier of Last Resort process during and after the 2021 to 2022 energy crisis, reducing the number of active domestic suppliers substantially from pre-crisis levels. Ofgem's retail market indicators show the market has since stabilised at a much smaller number of active suppliers than existed before the crisis.

Where can I check a supplier's current customer service record?

Citizens Advice publishes a quarterly star rating covering suppliers with more than 25,000 customer accounts, based on complaints data, call and message response times, and billing accuracy. This is a statutory publication rather than a marketing ranking, and it is updated four times a year.

How long does it take to switch energy supplier?

Ofgem's standard is up to 5 working days once the switch formally starts, preceded by a 14-day cooling-off period during which you can cancel without penalty. Most switches complete within this window with no need to contact your old supplier directly.

Should I fix my energy tariff now?

This depends on whether you value price certainty over the possibility of a lower bill if the cap falls. Fixing protects you if the cap rises again, but if forecasts of a cap reduction turn out to be accurate, a variable tariff could cost less over the same period. Neither outcome is guaranteed at the point you decide.