The UK's Financial Conduct Authority has begun an investigation into Wise co-founder and CEO Kristo Käärmann after he was fined by Her Majesty's Revenue and Customs (HMRC) for deliberately defaulting on his tax bill.
Last year, HMRC fined Käärmann over £350,000 after he submitted his personal tax returns late for the 2017/18 tax year.
Wise followed this up with an investigation with support from external legal counsel and then shared the details of its findings, assessment and actions with the FCA.
Now, the watchdog has commenced its own investigation, "regarding the regulatory obligations and standards to which Kristo is subject," says Wise in a statement.
David Wells, chair, Wise, says: "The Board takes Kristo's tax default and the FCA's investigation very seriously. After reviewing the matter late last year the Board required that Kristo take remedial actions, including appointing professional tax advisors to ensure his personal tax matters are appropriately managed.
"The Board has also shared details of its own findings, assessment and actions with the FCA and will cooperate fully with the FCA as and when they require, while continuing to support Kristo in his role as CEO."
Wise shares were down nearly three per cent, at 15:25 BST.