Autumn Budget 2026: IFS Warns Healey Needs Around £35 Billion in Tax Rises or Benefit Cuts

What happened: the Autumn Budget 2026 warning in full

The IFS, the UK’s best known independent tax and spending think tank, published its Green Budget 2026 on Monday 12 October 2026, funded by the Nuffield Foundation and produced in association with Barclays. Its press release is titled “Spending pressures, not fiscal headroom, are the Chancellor’s key Budget challenge”.

The core finding is simple. Higher inflation than expected in the spring, linked to the war in the Middle East, has squeezed the spending plans the Chancellor inherited from his predecessor, Rachel Reeves. Inflation pushes up the government’s borrowing costs, and it also eats into the cash budgets set for public services, so the same money buys less by the end of the decade.

IFS director Helen Miller said a steady-as-she-goes Budget is not an option. In the IFS’s own summary, avoiding real cuts to department budgets while also paying for higher defence spending could require tax rises or benefit cuts of around £35 billion. The IFS also warned that pencilling in spending plans the government would not be willing to live within would damage the plan’s credibility with markets.

The key numbers

One point worth showing plainly, because other reports today have used different headline figures: the two big parts of the pressure, about £25 billion for departments and £11 billion for defence, are separate lines in the IFS work. The IFS puts the combined need at around £35 billion. Our own check of the scale: £35 billion a year is about £96 million a day, and the £20 billion of headroom in the IFS scenario would cover only a little over half of it.

What it means for your money

Nothing changes today. No tax rate, allowance, benefit or bill has been changed by this report, and the IFS cannot change any of them. Only the Chancellor can do that, at the Budget on Wednesday 28 October 2026.

What this report does is set the size of the decision. If the Chancellor wants to protect public services and fund the defence pledge without borrowing more, the IFS work suggests the money has to come from higher taxes, lower benefit spending, or a mix of the two. If he does neither, the IFS says the result is real-terms cuts to services by the end of the decade.

For households, the practical points are these. First, do not act on Budget speculation: no rate or threshold has been announced, and acting early on a rumour can cost more than waiting 16 days. Second, the lines to watch on 28 October are tax thresholds and allowances, benefit uprating, and anything on energy or fuel costs, because those are the routes by which a £35 billion decision would reach wages, bills and benefits. Third, after the Budget, check that your pay reflects any threshold change correctly. Our guide to UK tax codes shows how to read the code on your payslip and what to do if it looks wrong.

Questions readers are asking

When is the Autumn Budget 2026? Wednesday 28 October 2026. It will be Chancellor John Healey’s first Budget.

Has the government announced £35 billion of tax rises? No. The £35 billion figure is the IFS’s independent estimate of the scale of tax rises or benefit cuts that could be needed. It is analysis published ahead of the Budget, not a government announcement, and the Chancellor may choose a different mix.

What is fiscal headroom? It is the small gap between the government’s plans and its own borrowing rules. The IFS puts it at around £20 billion in 2029-30 in a plausible scenario, down from £24 billion in the March forecast. A small gap means one bad economic surprise can break the rules.

What happens if the Chancellor does nothing? On the IFS analysis, department budgets set in cash terms would buy less as inflation bites, which means real-terms cuts to the quantity or quality of some public services by the end of the decade.

Source: Institute for Fiscal Studies, Green Budget 2026 and the press release “Spending pressures, not fiscal headroom, are the Chancellor’s key Budget challenge”, published 12 October 2026. Read the IFS press release. Full report: Green Budget 2026, full report.