Kristo Kaarmann, CEO and co-founder of Wise.Kristo Kaarmann, CEO and co-founder of Wise.

The CEO of Wise is being investigated by the U.K. regulators for failing to pay taxes.

The U.K. government department responsible for collecting taxes fined Kristo Kaarmann almost $400,000 for failing to pay his taxes in the last year.

Kaarmann paid what he owed along with late filing penalties after he submitted his personal tax returns late.

According to a statement from Wise on Monday, the U.K.'s Financial Conduct Authority is investigating the matter. Regulators are looking into the matter.

The investigation was not commented upon by theFCA.

The board of Wise hired lawyers to investigate Kaarmann. The investigation ended in the fourth quarter of 2021.

David Wells said the company's management takes Kaarmann's tax default very seriously.

Kristo was required by the Board to appoint professional tax advisers to ensure his personal tax matters are managed.

The Board has provided details of its own findings, assessment and actions with the FCA, as well as continuing to support Kristo in his role as CEO.

The probe may have consequences for Wise and its CEO. If regulators rule that Kaarmann fails the "fit and proper" test, he will have to step down from his job.

A Wise spokesman wouldn't comment on the investigation.

The news did not move the shares of Wise. Since its debut, the company's stock has lost over half of its value.

Wise was a darling of the U.K. start-up scene because it tackled hidden fees in foreign exchange and made a name for itself. Other areas of finance include banking and investments.