The Nuclear RAB levy, explained.

The Nuclear Regulated Asset Base levy funds the construction of Sizewell C while it is being built, rather than only once it generates. The Low Carbon Contracts Company, acting as revenue collection counterparty under the Nuclear Regulated Asset Base Model (Revenue Collection) Regulations 2023, sets one Interim Levy Rate in pounds per MWh for each quarterly obligation period and collects it from every licensed electricity supplier in Great Britain. Suppliers pass it through to customers, and it first reached bills for December 2025.

For the obligation period 1 July to 30 September 2026 the Interim Levy Rate is 4.488 pounds per MWh, which is 0.4488 pence per kWh. The Low Carbon Contracts Company published that determination on 27 April 2026. For the following period, 1 October to 31 December 2026, the rate falls to 3.754 pounds per MWh, confirmed in a stakeholder bulletin on 22 July 2026. A separate operational costs levy of 0.0028 pounds per MWh applies alongside it.

Regulated Asset Base. It is a way of financing infrastructure in which consumers pay towards the asset while it is being built, so the developer earns revenue during construction rather than only after the plant starts generating. The Nuclear Energy (Financing) Act 2022 created the framework for using it on a nuclear project, and the levy is the mechanism that collects those payments through electricity bills.

Collection started on 1 December 2025. The first determination, published on 12 August 2025, set the rate to zero to 31 October 2025 and 3.455 pounds per MWh from 1 November. Revenue commencement then moved to 4 November 2025, so November was set to zero and December was restated. A bill for any period before 1 December 2025 should carry no Nuclear RAB line at all.

The Low Carbon Contracts Company, in its role as revenue collection counterparty. Regulation 5 of SI 2023/254 requires it to determine the Interim Levy Rate at least 30 days before each quarterly obligation period begins and to issue a notice of that rate to every electricity supplier with a registered balancing mechanism unit. Ofgem is the economic regulator for the project and supplies the revenue figure the levy has to raise.

Regulation 5 sets it as the estimated cost of the quarterly obligation period, less the estimated income for that period, divided by the estimated electricity supply for the period. The estimated supply is the electricity all suppliers are expected to supply, less the electricity expected to be EII excluded electricity. If the result is below zero, the rate is determined as zero.

A supplier is billed on the electricity it supplied on each day, as determined through the Interim Information Volume Allocation Run. Nothing in the regulations grosses that volume up to a grid supply point, and line loss factors are not mentioned anywhere in them. On a customer bill the arithmetic is the plain one: metered kWh multiplied by the rate in force for the day. That is the main way it differs from AAHEDC, which is set and charged on volume at grid supply points.

Yes. Regulation 7 of SI 2023/254 works out a supplier interim rate payment on the electricity supplied on a day less any EII excluded electricity supplied on that day, and regulation 23 does the same for the operational costs levy. The same deduction is made from the estimated supply figure the rate is divided by. The Competition and Markets Authority reviewed the proposed exemption from 100 per cent of Nuclear RAB policy costs on a referral by DESNZ and DBT of 3 May 2024 and reported on 17 June 2024. This is a real difference from AAHEDC, which an EII certificate does not touch.

Because the rate can be revised inside the obligation period. The regulations provide for a data reconciliation of interim rate payments and for an adjusted interim levy rate taking effect part way through a period. It has happened once so far: the December 2025 rate was cut from 3.540 to 3.494 pounds per MWh on 7 November 2025, in part because Ofgem gave the counterparty a new revenue figure at Sizewell C commercial signing. A bill is priced on the rate in force on each day, not on the rate published 30 days before the quarter began.

Divide by ten. A rate of 4.488 pounds per MWh is 0.4488 pence per kWh, because a MWh is a thousand kWh and a pound is a hundred pence. Getting this wrong by a factor of a thousand is the most common mistake when checking the line, because the rate is published per MWh and almost every business bill prices per kWh.

No, although both are collected by the same body. The Low Carbon Contracts Company is the counterparty for both the Contracts for Difference supplier obligation and the Nuclear Regulated Asset Base scheme, and both are interim levy rates in pounds per MWh determined ahead of an obligation period. They are separate schemes made under separate instruments, they are determined separately, and the figures for one have no relation to the figures for the other.

Only by consuming less electricity supplied by a licensed supplier, or by holding an Energy Intensive Industries certificate, which removes the levy on the certified proportion of the electricity. There is no time band to shift out of, no capacity to reduce and no region to relocate to, because the rate is one flat national figure for the quarter. Generation consumed on site is never supplied by a supplier, so it never enters the volume the levy is charged on.