How much notice must my supplier give before a price rise?

Most price rises households experience today are not a supplier's own decision but the quarterly movement of the Ofgem price cap. From 1 October 2026 the cap for a typical dual-fuel direct debit home is £1,723 a year, up from £1,663³.

Supplier obligations under Ofgem's regulations

The 30-day notification rule sits in Ofgem's standard licence conditions: a supplier must notify the consumer at least 30 days in advance of the date on which the price increase takes effect¹. Alongside it, suppliers must cut their prices to the price cap level or below the level Ofgem sets, so a cap fall has to be passed on⁶. Ofgem has also required suppliers to offer at least one "low standing charge" tariff, following pressure on the daily charge households pay regardless of use⁷.

The rules reach further than pricing. Ofgem rules protect customers in debt where a supplier wants to install a prepayment meter, so arrears alone do not mean a forced switch to pay-as-you-go⁸. On credit balances, suppliers must reimburse customers on request unless there is a good reason not to⁹. Together these duties form the baseline a supplier must meet, and the notice rule is the part a household feels most directly when a bill is about to go up.

Setting and announcing changes to the price cap

The price cap sets a maximum amount suppliers can charge per unit of energy for customers on default tariffs, plus a limit on the daily standing charge¹⁰. It applies to customers on standard variable and prepayment tariffs, which is why most households that have never chosen a deal are covered by it¹¹. A fixed tariff is a contract at agreed rates, so the cap does not touch it until the fix ends.

The cap level moves with the costs suppliers face. When wholesale costs rise, the cap rises; Ofgem announced a 2% rise for the October to December 2025 period on that basis¹². The legal framework constrains how Ofgem can use it: under the Act, Ofgem cannot set different cap levels for different suppliers and must protect default tariff customers¹³. That is why the cap is a single national ceiling rather than a tool for targeting individual firms.

Cap increases by 4% to £1,723 for a typical dual-fuel household

Energy bills rose 4% from 1 October 2026, Ofgem announced on 26 August 2026, taking the average annual dual-fuel bill from £1,663 to £1,723 for the period to 31 December 2026¹⁴. The £1,723 figure is not a cap on any individual bill: it is what a typical dual-fuel household paying by direct debit would pay at the capped rates, and your own bill depends on how much gas and electricity you use.

The cap has moved repeatedly in recent periods. For 1 January to 31 March 2026, the cap made a bill of around £1,758 for a dual-fuel home with typical usage in Great Britain paying by direct debit¹⁵. Earlier levels include £1,738 for a typical household between 1 January and 31 March 2025¹⁶ and £1,849 for average dual-fuel direct debit households in April 2025, a rise driven by higher wholesale costs¹⁷. Prepayment customers saw the cap reach £1,803 for 1 April to 30 June 2025, a £113 increase on the previous level¹⁸.

Review dates and when fresh rates apply

Ofgem reviews and sets the cap every three months, fixing how much a supplier can charge for each unit of energy and the daily standing charge for the period ahead⁴. The Welsh Government's guidance states the same cycle: Ofgem updates the price cap every three months¹⁶. New rates take effect on the first day of the cap period they belong to, so the October 2026 rise applied from 1 October.

Ahead of each period, the benchmark consumption levels used to express the cap as an annual figure are specified in a statement at least 25 days before the start of the charge restriction period¹⁹. The next reviews are due on 25 November 2026 for the January to March 2027 cap, on 23 February 2027 for April to June 2027, and on 26 May 2027 for July to September 2027.

The quarterly cycle is itself relatively recent. Under the earlier methodology, updates occurred in February and August, applying to cap periods starting in April and October²⁰, and before that Ofgem worked out average supplier costs and revised the cap level every six months²¹. For a household on a variable tariff, the practical effect is that the unit rate can change four times a year, each time with the cap announcement preceding it.

Deemed contracts: the 'unduly onerous' ceiling on default rates

A deemed contract is what applies when you have not agreed a tariff with a supplier, most commonly after moving into a new home. Ofgem's rules state that the terms of deemed rate contracts should not be "unduly onerous"⁵. One way suppliers can ensure this is by making sure the profit derived from deemed rate customers is not significantly higher than the profit from contracted customers⁵.

The gap can be large in practice. Examples have been seen where deemed rate customers are charged more than double the rate of customers on contracts, and in one case study the standing charge on the deemed contract was nearly 14 times higher than the consumer could have achieved on contract⁵. Licence condition 7.7 obliges suppliers to send information about deemed contract rates, explaining the prices and informing the customer of cheaper options⁵.

If you have just moved home, checking what tariff you are on is the quickest way out of a deemed rate; our page on the tariff you are on when you move into a new home covers this.

Where Ofgem's help for individual customers begins and ends

Ofgem's role in a dispute is limited. It does not directly get involved in complaints about energy suppliers or network operators, and does not investigate individual disputes²². Complaints go first to the supplier, and then to the Energy Ombudsman if unresolved. What Ofgem does instead is monitor suppliers' compliance with its rules: it has stated it "will be closely monitoring supplier compliance and will continue to take firm action against suppliers who fall short of their requirements"²³.

Some protections work without any complaint. Under the back-billing rules, an energy supplier cannot charge domestic or microbusiness consumers for energy used or charges more than 12 months old due to the supplier's error²⁴. Where a supplier has not given reasonable notice of a price rise, the complaint route runs to the supplier first².

If affordability rather than notice is the problem, suppliers can be asked to agree a payment plan, payment break or reduction, review payments and debt repayments, and give access to hardship funds²⁵. Asking early, before arrears build, keeps the widest set of options open. For the wider picture of what suppliers must offer, see tariff rules and consumer protections, and for how tariff choices affect your independence from price rises, see tariffs and household energy independence.