A former UBS private banker charged with helping a US billionaire evade income taxes is expected to enter a guilty plea in federal court next month, according to court documents.

A judge “will ask for a full confession” from Bradley Birkenfeld, the court clerk said in a court filing on Friday, giving notice of a change of plea hearing set for June 9. Mr Birkenfeld, who was indicted this month for allegedly conspiring to defraud the US, had previously pleaded not guilty.