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Energy & environment · UK-wide

The Green Party's carbon tax: what would it add to your bills?

A rising charge on fossil fuels — starting at £120 for every tonne of CO2 emitted, and climbing to £500 a tonne within a decade — pitched as the engine that pays for the party's other spending plans.

Status: Proposal — not law Region: UK-wide Party: Green Party (Zack Polanski) Active: July 2026

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What's being proposed

Alongside its wealth tax, the Green Party's tax package includes a carbon tax — a charge on fossil fuels set initially at £120 per tonne of CO2 emitted, rising over ten years to a maximum of £500 per tonne. The party says it would raise up to £80bn a year at full strength, revenue it would recycle into the insulation programme and bill support covered in our energy bills explainer, alongside wider public spending.

Where it comes from

The carbon tax sits inside the wider £115bn-a-year 2026/27 tax package set out in the Greens' economic platform under leader Zack Polanski. Unlike the wealth tax, which only touches a small number of very rich households, a carbon tax reaches into everyday costs — heating, petrol, and anything made or transported using fossil fuels — which is what makes it both a bigger potential revenue raiser and a bigger personal cost for most households.

How it would work

  • A price is charged per tonne of CO2 released by burning fossil fuels — gas, petrol, diesel and so on.
  • It starts at £120/tonne and rises in steps to £500/tonne within ten years.
  • Some of that cost is paid directly (higher pump and gas prices); some is passed through indirectly in the price of goods and services that use fossil fuels to produce or transport.
  • Revenue is earmarked for the green transition — insulation, renewables investment and bill support — rather than general spending.
The calculator below estimates only the direct cost — your home energy use and driving. It can't capture the indirect cost passed through in everyday goods, which independent analysts say would add further to the total.

The case for and against

Supporters argue

  • A rising, predictable carbon price gives households and businesses a clear signal to switch away from fossil fuels over time.
  • It could raise very large sums to fund insulation and clean energy, cutting bills structurally rather than with one-off support.
  • Revenue recycled into insulation and bill support could offset the cost for lower-income households specifically.

Critics argue

  • The Institute for Fiscal Studies and other independent analysts are sceptical the full £80bn would materialise — the more the tax succeeds at cutting emissions, the less it raises.
  • Without generous, well-targeted rebates, a carbon tax this size would land heavily on households that can't easily switch — rural drivers, older housing stock, lower incomes.
  • At £500/tonne, the eventual cost to a typical household's heating and driving would be substantial, as the calculator below shows.
Interactive calculator

Estimate what the carbon tax could add to your costs

Enter your annual home energy bill and typical driving, and see the estimated extra cost at the £120/tonne starting rate and the £500/tonne rate it reaches within a decade.

A rough, direct-cost estimate — not a forecast. This is not law. It converts your energy bill and mileage into an estimated tonnage of CO2 using published government conversion factors, then applies the proposed carbon price. It excludes indirect costs passed through in the price of goods and services, and assumes no behaviour change (switching to an EV, insulating, driving less) — which is the whole point of the policy. Not financial advice.

Your energy & driving

Home energy is converted to tonnes of CO2 by scaling your bill against a typical dual-fuel household's usage (≈2,700 kWh electricity, ≈11,500 kWh gas) and DESNZ average grid-carbon-intensity and gas conversion factors, giving roughly 2.5 tonnes CO2/yr for a typical bill. Driving is converted using an average petrol car's emissions factor of roughly 0.27kg CO2 per mile. Diesel, hybrid, EV and actual usage will vary the real figure considerably. Not financial advice.

Sources & further reading

Figures are illustrative and based on the party's stated proposals and standard government conversion factors; real-world costs and revenue are contested and would depend on final scheme design. General information, not financial, legal or tax advice.

Frequently asked questions

Is there a UK carbon tax already?

Not a broad household carbon tax like this one. The UK has a carbon price for large industrial emitters and power generators (the UK Emissions Trading Scheme), but nothing yet that directly prices household gas and petrol use this way — that's what the Green Party is proposing.

How much would the Green carbon tax cost me?

It depends on your home energy use and driving. Enter your annual energy bill and mileage in the calculator above to see an estimate at both the £120/tonne starting rate and the £500/tonne rate it would reach within a decade.

Would low-income households be protected?

The Green Party says carbon tax revenue would fund insulation and bill support that could offset the cost for lower-income households, but the party hasn't published a detailed rebate scheme, so the net effect for any individual household is uncertain.

Is the Green Party's £80bn revenue estimate realistic?

Independent analysts, including the Institute for Fiscal Studies, are sceptical. A carbon tax is self-limiting by design — the more successful it is at pushing people away from fossil fuels, the less revenue it raises over time, making the full £80bn figure unlikely to be sustained.