Taxi drivers and chip shop owners are among those being investigated by tax inspectors over offshore bank accounts and evasion.
HM Revenue and Customs (HMRC) has identified around half a million Britons using offshore accounts, it was revealed.
An official has said that more and more middle-class people are taking advantage of the tax-free havens.
The official told The Sunday Times that those under investigation included “chip shop owners, taxi drivers and landladies from Blackpool”.
They could be facing large penalties if they are found to have dodged their payments with HMRC looking to raise billions in interest, tax and fines.
They may consider seeking financial advice in the future rather than using offshore alternatives.
The potential offenders have been identified through enforced data-sharing with banks and whistleblowers. Individuals have also been checked on a new IT system that allows their pay, lifestyle and assets to be compared with tax paid.
Eight arrests have been made and five people interviewed under caution in recent weeks but officials expect many more to follow.
Treasury Minister David Gauke said: “The options for hiding money offshore to evade UK tax are narrowing all the time and I would strongly urge anyone who is at all concerned that they may not have been paying the right tax on their offshore investments to talk to HMRC.
“The Government has made £917 million available to HMRC to tackle tax cheats and some of this money is already being very effectively deployed against off shore tax evaders.”