Ofgem introduces new lower TDCVs from October 2023

Ofgem introduced new lower Typical Domestic Consumption Values (TDCVs) for all its relevant publications from October 2023, the House of Commons Library reports¹. The assumed typical annual gas consumption for a dual fuel household fell from 12,000 kWh to 11,500 kWh, and assumed typical electricity consumption fell from 2,900 kWh to 2,700 kWh¹.

TDCVs are industry standard values for the annual gas and electricity usage of a typical domestic consumer². The energy price cap sets the maximum unit price per kWh and the maximum daily standing charge suppliers can charge for gas and electricity, and varies by energy supply region, payment method and type of electric meter². The cap is communicated to consumers through TDCVs, so the assumed consumption level determines the headline annual figure attached to each cap period².

The Library states the effect plainly: the change "makes an average bill for typical consumption look lower, even if prices per unit of energy are unchanged", and "does not affect trends in prices or bills"¹. Fuel poverty calculations are based on the price of fuels as set by the cap, not the communicated TDCV figure².

The change came alongside a falling cap. The price cap for July to September 2023 was £1,766 for current levels of typical consumption, with unit prices 27% lower than under the Energy Price Guarantee for gas and 9% lower for electricity; because the annual level was below the EPG, customers on standard variable tariffs saw prices fall for the first time since October 2020¹. The cap fell further to £1,641 in October 2023, the month the new TDCVs took effect, then rose to £1,723 in the first quarter of 2024¹.

Source: Scottish Government, GB averages for a household paying by direct debit². The 2022 and 2023 weighted average prices reflect rates paid under the Energy Price Guarantee rather than the price cap at the time².

Why it matters for households

The TDCV change did not alter what any household pays per unit of gas or electricity. It altered the yardstick used to describe the cap. A lower assumed consumption level produces a lower quoted annual bill for the same unit rates, so figures published before October 2023 and after it are not directly comparable as measures of what a typical household spends¹.

The practical effect is on how bills are reported and compared. Households using more than the assumed 11,500 kWh of gas or 2,700 kWh of electricity pay more than the quoted annual figure; those using less pay less. Annual bills are not capped, and prices also vary by region and are higher for customers paying by quarterly bills¹.

The TDCVs were revised again in July 2026, reflecting further falls in median average household consumption: the assumed gas level was cut by 17% to 9,500 kWh and electricity by 7% to 2,500 kWh¹. The Scottish Government's fuel poverty modelling records the same July 2026 revision². Most statistics in the Library briefing now use the July 2026 lower TDCVs, and unit prices are also published because they are not affected by consumption assumptions¹.

What happens next

Under the July to September 2026 direct debit price cap the average annual bill for typical gas and electricity consumption is £1,663, which the Library says is 18% higher than the recent low in July to September 2024¹. The cap is reported to increase by 4% in the fourth quarter of 2026, with a further 9% forecast for the first quarter of 2027¹. Average gas unit prices under the direct debit cap are reported to rise 9% to 8.0 p/kWh in October 2026, with electricity up 1% to 26.3 p/kWh, the gas standing charge up 0.7 p/day and the electricity standing charge down 2.4 p/day¹. The electricity figures include the effect of the government's decision to remove VAT from electricity bills for six months from October 2026¹.