Question to the HM Treasury:

To ask the Chancellor of the Exchequer, pursuant to the answer of 9 December 2025 to Question 95649 on Inflation, whether any public body undertakes assessments of the adequacy of GDP deflator forecasts.

Forecasts for the UK economy, including assessments of the impact of policy decisions, are the responsibility of the independent Office for Budget Responsibility (OBR).

The OBR publishes its forecast in the Economic and Fiscal Outlook (EFO). The OBR’s latest EFO can be found here: Economic and fiscal outlook – November 2025 - Office for Budget Responsibility. The OBR’s EFO includes a forecast of the GDP deflator.

The OBR is required to produce a Forecast Evaluation Report (FER) each year under the Budget Responsibility and National Audit Act (2011). The OBR is required to explain reasons for divergence between its forecasts and subsequent outturns, to support future forecast improvements.

The latest Forecast Evaluation Report can be found here: Forecast evaluation report 2025 - Office for Budget Responsibility . Evaluation of the GDP deflator can be found on pages 29-30.