The figure relates to the yield from compliance investigations into self-assessed business taxes by HMRC local teams for the year ending March 31 2016, obtained via a freedom of information request.

UHY Hacker Young says its analysis suggests that because tax investigations into large businesses may be becoming less profitable, HMRC has shifted some of its focus to investigating SMEs, as it faces increased pressure from the Exchequer to boost tax take.

The firm suggests that this is partly because large businesses are often better resourced and able to employ in-house tax specialists, who can close down or limit HMRC’s investigations when its approach gets unnecessarily aggressive. Smaller businesses are often unable to do the same, and may therefore prove to be a more profitable target for HMRC.

UHY Hacker Young adds that, on the other hand, small and mid-sized businesses could be affected by time and budgetary constraints, or a lack of financial experience when it comes to self-assessing their tax affairs, which could make them more prone to errors.

Roy Maugham, tax partner at UHY Hacker Young, said: ‘HMRC are showing signs of beginning to exhaust yields from investigations into large businesses. Many small and mid-sized companies may not have been at the top of HMRC’s agenda in the past, but are now coming under the spotlight.

‘There is increasing pressure on small and mid-sized businesses to spend their time and money on systems to ensure that tax affairs are accurate and up to date. Without adequate care, small businesses are at risk of being pulled up over minor mistakes or small disparities, which could incur disproportionately heavy fines and penalties.’

Last year, HMRC also increased the number of full-time employees it is affluent unit by 20%, from 327 to 395, as it increases its investigations into middle class taxpayers. the affluent unit investigates the tax affairs of UK residents with an annual income of over £150,000 or a net worth of £1m.