[holding answer 6 December 2007]: There are no robust estimates of the revenue lost specifically to tax evasion for each of the last five years. However, HMRC have recently published two documents on tax losses alongside the 2007 pre-Budget report.
Measuring Indirect Tax Losses 2007 presents the latest annual update of HMRC's estimates of revenue losses for indirect taxes.
Developing Methodologies for Measuring Direct Tax Losses includes estimates of direct tax losses for individuals subject to income tax self assessment, small and medium-sized companies, and small and medium-sized employers.
While the estimates given in these documents include evasion they also encompass other causes of losses, including avoidance and error.