Question to the HM Treasury:

To ask the Chancellor of the Exchequer, what assessment she has made of the potential impact of leaving the European (a) Customs Union and (b) Single Market on growth.

The UK economy has experienced significant disruption in recent years due to a range of factors including Covid-19, supply chain disruption and the invasion of Ukraine by Russia. It remains challenging to separate out the effects of leaving the Customs Union and Single Market from wider global trends affecting the UK economy.

It is for the Office for Budget Responsibility (OBR) to provide independent and authoritative analysis and forecasting for the UK public finances. The OBR has estimated that productivity will be 4% lower in the long run than it would have been had the UK not withdrawn from the EU, and that imports and exports will eventually both be 15 per cent lower than had we stayed in the EU. The OBR estimated in March 2024 that 40% of this impact has already materialised.