How much is the Sizewell C nuclear charge on energy bills?

The Sizewell C RAB surcharge added £14 per year to bills from January to March 2026, then reduces to £13 per year from April 2026 onwards. The charge is rolled into the unit rate rather than appearing as a separate line on bills, so most households will not notice it directly.

Why are households paying for Sizewell C before it is built?

Sizewell C is being funded through the Regulated Asset Base model, where investors receive a return during construction rather than only after the plant opens. This reduces financing costs and therefore the eventual electricity price from the plant, but means bill payers start contributing before the station generates any power.

When will Sizewell C nuclear power station be finished?

Sizewell C is not expected to open until the mid-2030s. The total project cost is over £20 billion, making it one of the largest infrastructure projects in UK history. Construction has not yet begun, so households will be paying the RAB surcharge for over a decade before any electricity is generated.

Will the Sizewell C charge apply if I am on a fixed energy tariff?

If you are already on a fixed tariff, the charge will not affect your bills until your fix ends - your rates are locked in regardless of changes to the price cap or policy costs. When you renew or switch to a variable tariff, the Sizewell C surcharge will be included in the unit rate you are quoted.

What other policy costs are included in UK energy bills?

Energy bills include several policy cost components beyond the Sizewell C charge. The largest is the renewables subsidy, which adds around £120 per year, followed by energy efficiency schemes at approximately £45 per year and the Warm Home Discount at around £46 per year. Together these policy costs add over £200 per year to the typical household bill.

Sizewell C Nuclear Surcharge: What It Means for Bills

What's Happening?

From 1 January 2026, a new charge is being added to your electricity bill. It's to help build Sizewell C — a nuclear power station in Suffolk that won't generate any electricity for years.

Yes, you read that right. For the first time ever, part of your bill is going towards building a power plant before it actually produces any power.

£14

Added per year (Jan-Mar 2026)

£13

Per year from April 2026

2030s

When plant might open

£20bn+

Total project cost

The Sizewell C Timeline

You pay now, power comes later

January 2026

Charges start appearing on your bill

~£14/year added to electricity bills

2026–2034

Construction phase

You keep paying while the plant is built

Mid-2030s (estimated)

Plant starts generating power

Finally produces electricity for the grid

Why Are We Paying Now?

Building nuclear plants is incredibly expensive — we're talking tens of billions of pounds. The government decided that if customers chip in small amounts during construction, it reduces the overall cost in the long run.

The idea is:

Lower risk for investors = cheaper financing
Cheaper financing = lower bills when the plant eventually opens
Nuclear provides reliable power that doesn't depend on wind or sun

Whether you agree with that logic or not, the decision has been made. The charge is now law.

How Much Will It Add?

Nuclear Charge on Your Bill

Expected annual cost per household

January – March 2026

£14 per year added to bills. Slightly higher because it includes catching up on costs from December 2025.

April 2026 onwards

~£13 per year. This is expected to stay roughly the same through 2026, but could rise as construction progresses.

Where does it appear on your bill? You won't see a separate line item. It's rolled into your electricity unit rate — so your price per kWh goes up slightly.

The Bigger Picture: Policy Costs on Your Bill

This is just one of several "policy costs" on your bill. You're already paying for things like:

Policy Costs Already on Your Bill

Government programmes funded through energy bills (£/year)

Renewables subsidies: Funding for wind and solar farms
Energy efficiency: Grants for home insulation
Warm Home Discount: Support for low-income households
Nuclear RAB (new): Building Sizewell C

These add up. They're part of why your bill doesn't just track the actual cost of gas and electricity — there's a whole layer of government programmes built in.

Does This Affect Fixed Deals Too?

Yes. Most suppliers will build this cost into both standard rates AND fixed tariffs. So switching to a fixed deal won't necessarily avoid it.

That said, there are still competitive deals out there. If you lock in a good fixed rate now, you could protect yourself from future increases — not just from nuclear charges, but from all the other costs that keep getting added to bills.

Key Takeaways

✓ New charge starts 1 January 2026

⚛️ Pays for building Sizewell C nuclear plant

⚠ £14/year added Jan–Mar 2026

⚠ ~£13/year from April 2026 onwards

💡 Rolled into unit rate — no separate line on bill

💡 Applies to standard and fixed tariffs