Question to the HM Treasury:

To ask Mr Chancellor of the Exchequer, what estimate his Department has made of the change in levels of tax evasion in the last 10 years.

The latest available estimates of the amount of money the Exchequer loses to tax evasion over the last five years (the latest year being 2015-16) are published annually in the Chapter 1 of the ‘Measuring tax gaps’ publication, in Table 1.5.

https://www.gov.uk/government/statistics/measuring-tax-gaps

Further ‘Measuring tax gaps’ online tables are published giving the estimate of money and the percentage of total theoretical liabilities lost to tax evasion since 2009-10.

https://www.gov.uk/government/statistics/measuring-tax-gaps-tables

There is no comparable data for years prior to 2009-10.