A carbon budget is a legal limit on the total amount of greenhouse gas the UK may emit over five years. Budgets are the stepping stones between today’s emissions and the net zero target for 2050, and they are measured in million tonnes of carbon dioxide equivalent (MtCO2e).
How budgets are set
The Climate Change Act 2008 requires the government to set each budget about 12 years ahead. The independent Climate Change Committee (CCC) advises on the level, the government proposes it and Parliament approves it by order. The first three budgets, covering 2008 to 2022, were met.
| Budget | Period | Level |
|---|---|---|
| Fourth (CB4) | 2023–2027 | 1,950 MtCO2e |
| Fifth (CB5) | 2028–2032 | 1,725 MtCO2e |
| Sixth (CB6) | 2033–2037 | 965 MtCO2e (78% below 1990 by 2035) |
| Seventh (CB7) | 2038–2042 | 535 MtCO2e (about 87% below 1990) |
The sixth and seventh budgets are the first to include international aviation and shipping. Parliament approved the seventh budget in June 2026 at the level the CCC recommended.
Progress so far
The CCC reports to Parliament every year. Its June 2026 report put provisional UK emissions for 2025 at 407 MtCO2e, about 50% below 1990. It judged the fourth budget highly likely to be met and found credible policies in place for the fifth. The sixth is achieved only narrowly on the government’s own pathway, which leans heavily on engineered removals, and plans for 17% of the reductions needed in that period were judged insufficient.
Why it matters
A budget does not prescribe how emissions fall. It sets the total, and the government must publish policies to stay within it. Missing a budget would be a breach of the Act, which is why the CCC’s assessment of delivery plans gets close attention.
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