Question to the HM Treasury:

To ask the Chancellor of the Exchequer, what assessment (a) HM Treasury and (b) the Government Actuary Department has made of the accuracy of the GDP deflator forecasts by the Office for Budget Responsibility.

Economic forecasts, including assessments of the impact of policy decisions, are the responsibility of the independent Office for Budget Responsibility (OBR).

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

The latest FER can be found here: Forecast evaluation report 2025 - Office for Budget Responsibility. This includes information about the GDP deflator on Page 29-30.