Households face a sharp rise in energy costs from July, with consultancy Cornwall Insight projecting an increase of roughly £332 a year for a typical dual-fuel home.
The firm estimates the annual bill under Ofgem's price cap for July to September would reach about £1,973, up from the current level of £1,641.
Cornwall Insight is updating its outlook weekly because of large swings in wholesale prices.
Ofgem will announce the next price cap on 27 May, using wholesale market data from March, April and May.
The regulator adjusts the cap every three months; it limits the per-unit charges on standard default tariffs, but actual bills depend on how much gas and electricity a household uses.
Wholesale energy costs climbed sharply during the first weeks of March, but the final cap will reflect price movements across the rest of the three-month window.
The cap influences roughly 19 million households in England, Wales and Scotland who are on standard variable or default direct-debit tariffs.
Political debate is rising over whether the government should step in to blunt the impact of any big July increase.
Ministers are weighing up whether any support should be universal or focused on low-income and vulnerable families — the latter approach would direct more help to those in need while lowering public costs.
Chancellor Rachel Reeves has indicated support would be targeted to protect poorer households, and the Treasury is reportedly preparing several options.
By contrast, the broad emergency support paid out after Russia's 2022 invasion of Ukraine applied to all bill payers and cost more than £35bn.
Last November the government cut charges that reduced bills by £150 for households.
Without that measure, Cornwall Insight says the typical annual bill would have exceeded £2,000 under its latest scenario.
The recent surge in global fuel prices has prompted international calls to curb demand.
The International Energy Agency has outlined steps countries and businesses can take to lower energy use, which could help ease pressure on prices and on consumers.
Suggested measures range from encouraging public transport and car-sharing to reducing air travel and allowing more remote working.
Some nations have already set limits on air-conditioning and shortened working hours for public servants to conserve energy.
The IEA also recommends protecting supplies of liquefied petroleum gas for essential uses by shifting certain vehicles to alternative fuels and taking steps to cut non-essential consumption.
Executive director Fatih Birol warned that, without a rapid de-escalation in the Middle East, strains on energy markets and economies are likely to grow.
For households, the next few weeks of wholesale price movement will be crucial in determining whether the July cap outlined by Cornwall Insight is confirmed, rises further, or eases.
Consumers can influence their own bills by reducing usage, but wider relief will depend on government decisions and market developments.
