The national audit office puts the cost at 850bn, which is 58% of 2008′s nominal GDP. The BoE has a similar estimate of almost 60% of GDP. This is the direct impact of government intervention to support the banks. It doesn’t include the indirect costs of a weaker economy – lower tax revenues, higher benefit spending. In 2007/08, income tax and capital gains amounted to 208bn (that’s corporate and household income and wealth).