Taxi drivers, market traders, restaurateurs and buy-to-let landlords are being targeted by new anti-tax evasion teams set up by HM Revenue & Customs.
Following on from similar crackdowns in the plumbing and electricity trades, tax inspectors are now turning their attention to other self-employed people and those that run restaurants or let property.
The inspectors will visit businesses and private addresses to carry out on the spot inspections of people's accounts.
David Gauke, the Exchequer Secretary, said that its specialist taskforces had already pulled in £650m in extra taxes and fines in the 2011-2012 tax year.
"We have made it clear that we will not tolerate tax evasion – everyone needs to pay the taxes they owe in full. We are determined to crack down on the minority who choose to break the rules. It is not fair, that at a time when most hard-working people are paying the right tax, others are trying to get out of paying what they should."
HMRC launched 12 taskforces last tax year with 30 more due to follow in the course of this year. But, they have a long way to go to reach the Government's long term target of recovering £7bn in unpaid taxes by 2016.