Hunch. The Budget papers of 28 October put the 2026-27 deficit at 4.5% on the measure the IMF uses, though the IMF's own table still says 3.8%.
Resolves YES if the first figure in the April 2027 IMF World Economic Outlook puts UK general government net borrowing for 2026 at 4.3% of GDP or more, NO at 4.1% or less, and VOID at exactly 4.2%, with the report date used if it comes after 20 April. Later revisions do not count, and if the IMF table does not open, The Guardian and BBC News reports of the April report decide.
We looked for cases where the Office for Budget Responsibility gave its borrowing forecast for the current year on a Budget day in the autumn, and the IMF later gave its first figure for that whole year in April. We found five such Budgets, from 2017 to 2025. Before 2017 the autumn forecast came with a smaller Autumn Statement. Four times the IMF’s first figure showed a bigger deficit than the forecast.