The US and Swiss governments formally signed a new double taxation agreement yesterday, following an earlier deal between the two countries in May this year.

The treaty calls for mandatory arbitration in some tax cases, and changes the treatment of dividends when a shareholder is a pension or retirement fund.

“As has been the case with past DTAs, so-called 'fishing expeditions' are not permissible. These provisions are not applicable retroactively: In terms of the exchange of banking information, the effective date is today, the day of the signing,” the Swiss government said in a statement.

Relations between the Swiss and US governments have been under strain in recent months as the US has launched a highly vocal campaign to prise open centuries-old Swiss bank secrecy laws and track down suspected US tax evaders. The Swiss banking sector has complained that countries such as the US and UK have been hypocritical, since these nations also operate offshore tax havens.