Barnett formula

The Barnett formula is the mechanism by which the UK Treasury calculates the block grants paid to Scotland, Wales, and Northern Ireland. Devised by Chief Secretary to the Treasury Joel Barnett in 1978, it adjusts devolved budgets based on per-capita changes in comparable English public spending. If England increases NHS spending by £1 billion, Scotland receives a population-proportionate share automatically, regardless of local need. The formula has never been enshrined in statute and operates by Treasury convention.

In the 2026 Holyrood election, the formula became politically salient because Scottish income tax changes interact with it. If Scotland raises or cuts income tax, the Treasury adjusts the block grant by a corresponding amount to avoid double-counting the fiscal benefit or loss. This block grant adjustment means policies like the Scottish Conservatives' proposed pensioner tax cut may yield less fiscal space than their headline cost suggests, which is the basis for the IFS critique of the Get Scotland Working manifesto.

The formula has faced sustained criticism from Welsh Government ministers, who argue it undervalues Wales relative to need, and from economists who see it as a blunt instrument for a more complex devolved settlement. Pressure for a needs-based replacement has grown since the 2010s, but no UK Government has moved to replace it, partly because any change would create clear winners and losers among the devolved nations.