Brexit is Costing the UK £100 Billion a Year in Lost Output. The UK is facing a hefty economic blow due to the Brexit process, with the cost of the process estimated to be around £100 billion. This figure is based on analysis from economists and financial experts, who have calculated the costs of leaving the European Union. The costs include trade tariffs, reduced investment, and lost productivity. This has had an effect on businesses across the country and has left many feeling uncertain about their future prospects.