On Oct. 29, HM Treasury published GDP deflator figures through fiscal 2025-26 and forecasts from the Office for Budget Responsibility (OBR) through 2031-32, presenting an official measure of domestic inflation.
The Treasury describes the deflator as a broad way to track inflation in the domestic economy. The release separates historical outturns from forecasts: the observed record spans 1955-56 to 2025-26, and the projection period runs from 2026-27 to 2031-32. The forecast years correspond to calendar years 2026 through 2031.
The historical section is based on the Office for National Statistics (ONS) Quarterly National Accounts released Sept. 30. Treasury's fiscal-year deflator figures from 1955-56 through 2025-26 use ONS series L8GG. Its calendar-year data for 1955 through 2025 come from series MNF2, keeping the two annual formats distinct in the published tables.
The forecast values reflect OBR projections as of the Oct. 28 Budget. The Treasury says the historical outturn may reflect a more recent version of ONS GDP outturn, depending on when the OBR updates its deflator forecasts. Those updates usually take place at a Budget or Autumn Statement, so the version used can depend on the timing of the forecast cycle.
The release also includes money GDP data for both calendar and fiscal years without seasonal adjustment. For fiscal years, it provides an additional seasonally adjusted series. ONS series BKTL supplies the unadjusted figures, while series YBHA is used for the adjusted fiscal-year data.
The next update to the GDP deflator is due after the ONS Quarterly National Accounts release scheduled for Dec. 22, 2026. That publication is the next stated update point for the series.
