The Internal Revenue Service has awarded a former UBSbanker $104m for revealing a tax evasion scheme that cost the US government billions of dollars in lost taxes and resulted in criminal charges against Swiss banks and top executives.

Bradley Birkenfeld, a former Switzerland-based banker who called himself “Tarantula”, reported allegations of tax evasion at UBS to US authorities in 2007. His reward is believed to be the largest bestowed on a whistleblower.

Mr Birkenfeld is widely credited with uncovering the scheme, which led to UBS pleading guilty to criminal charges and paying $780m to settle with the Department of Justice. As a result, the US government has collected $5bn in back-taxes. “The IRS today sent 104m messages to whistleblowers around the world that there is now a safe and secure way to report tax fraud and that the IRS is now paying awards,” Mr Birkenfeld’s lawyers said.