UK inflation jumps to 3.5% in September on soaring fuel prices

UK consumer price inflation jumped to 3.5% in September 2026, marking an acceleration from 3.1% the previous month and reaching its highest rate since October 2025, according to official figures released on Wednesday. The increase exceeded the 3.4% consensus anticipated by economists, placing renewed strain on household budgets and delivering a difficult pre-Budget challenge to Chancellor John Healey.

The primary driver behind the monthly jump was the cost of filling up a vehicle. According to the Office for National Statistics (ONS), transport prices surged by 6.6% year-on-year, up sharply from 4.6% in August. Average petrol prices rose by 8.2p per litre to 169.5p, while diesel costs hit their highest level since July 2022. Analysts attribute these pressures directly to ongoing conflicts in the Middle East and Europe, which have squeezed global oil supplies and constrained refining capacities. In addition to transport fuels, upward contributions came from rising airfares, computer games, and live events, though partially offset by milder increases in hotel accommodation costs.

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Underlying inflation measures also showed persistence. Core CPI inflation, which strips out volatile energy and food components, edged higher from 2.6% to 2.8%, while services inflation accelerated from 3.4% to 3.7%. Food inflation remained unchanged at 1.3%. Danni Hewson, head of financial analysis at AJ Bell, warned that the compounding effects of raw material cost increases, higher transportation expenses, and rising business overheads will weigh heavily on consumer confidence as households brace for further energy bill pressures.

The hotter-than-expected inflation data has cemented market expectations that the Bank of England will raise interest rates when its Monetary Policy Committee meets next month. Financial traders are pricing in roughly 96% odds of a 25 basis point increase on 5 November, which would bring the benchmark rate up from its current level of 3.75%.

Simultaneously, the ONS released public finance figures showing that UK public sector net borrowing reached £24.5 billion in September, £1.8 billion higher than the same month last year. Cumulative borrowing for the financial year to date has climbed to £97.8 billion, exceeding the Office for Budget Responsibility's forecast by £6 billion. Crucially, public sector net debt surpassed £3 trillion for the first time, pushed upward by higher debt interest costs linked to inflation. Ruth Gregory, deputy chief UK economist at Capital Economics, stated that the borrowing figures painted a dismal picture ahead of the fiscal address.

Political friction was immediate. Shadow Chancellor Andrew Griffith accused the government of losing control of the economy and urged the Chancellor to curb wasteful spending. Responding to the pressures, Chancellor John Healey defended the government's approach, emphasising fiscal discipline while pointing to recent international recognition and domestic energy security measures such as the approval of the Jackdaw gas field.

Beyond immediate market reactions, September's CPI figure carries substantial statutory weight. By law, the index serves as the benchmark for annual increases to various welfare benefits, including the personal independence payment and carer's allowance, while the state pension is separately projected to rise by 3.9% under the triple lock based on earnings growth.

What to watch next

• 28 October 2026: Chancellor John Healey delivers the annual autumn Budget, detailing tax and spending plans against a backdrop of higher borrowing.
• 5 November 2026: The Bank of England announces its latest interest rate decision, with markets heavily anticipating a 25 basis point hike.
• October Energy Price Cap: Household utility costs shift as regulatory caps adjust heading into the winter heating season.