But Syedur Rahman of business crime solicitors Rahman Ravelli does not believe these figures alone can be an accurate gauge of HMRC success.

New research has revealed that COP8 and COP9 investigations led by HM Revenue and Customs (HMRC) have brought in a total of £610M for the Treasury in three years.

The results, obtained through a Freedom of Information Report (FOI), showed that over the financial years 2016-17, 2017-18 and 2018-19 COP8 investigations generated £262,228,346 and COP9 investigations £348,064,622. Read more about HMRC Tax & VAT Investigations.

COP9 (Code of Practice 9) cases involve criminal investigations being started launched when HMRC suspects fraud has occurred. COP8 (Code of Practice 8) cases are civil inquiries commenced when there has been a deliberate - but not criminal - avoidance of tax or where an individual has used a scheme to avoid or reduce tax liabilities.

In the three-year period, 1,473 COP9 and 924 COP8 investigations were opened. 610 COP9 and 260 COP8 inquiries ended with a penalty charge being imposed.

The amount of COP9 investigations opened each year has dropped year on year, from 549 in 2016-17 to 438 in 2018-19. But the proportion of cases closed with a penalty imposed has increased each year.

While there is little doubt that recent years have seen HMRC take an increasingly hard line on suspected avoidance – meaning that more people need to take advice if they are concerned that they are not compliant – the figures released under FOI cannot be viewed as the full picture. They certainly should not be taken as a full assessment of HMRC's effectiveness.

In order to have a greater understanding of whether or not HMRC's generated figures for COP8 and COP9 investigations during the relevant periods are significant achievements, there needs to be further examination of data. Any true assessment of HMRC's effectiveness in this area of its work would need to involve the figures for what HMRC was alleging tax payers owed so they could be compared to how much HMRC actually recovered by way of settlement and penalties.

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