Report someone to HM Revenue and Customs (HMRC) if you think they’re evading tax.
Don’t try to find out more about the tax evasion or let anyone know you’re making a report.
For example, they might be:
not telling HMRC about tax they owe (for example on business profits)
keeping business ‘off the books’ by dealing in cash and not giving receipts
hiding money, shares or other assets in an offshore bank account (‘offshore tax evasion’)