Next year’s Forecast evaluation report will look back at what will probably be the largest official economic forecast errors ever, reflecting the full effect of the coronavirus pandemic on the economy and public finances in 2020-21. In this year’s brief report, we look back at our March 2018 and March 2019 forecasts for 2019-20. Both significantly over-estimated GDP growth and under-estimated the budget deficit. At the time, we thought the largest uncertainties around our forecasts stemmed from productivity and the Brexit negotiations. But it is the early effects of the pandemic in the final weeks of 2019-20 that explains most of the forecast differences.
