"It is clear that a business model based on untaxed assets has no future," Rohner told the Swiss-German daily Tages-Anzeiger when asked about a pending tax deal between Bern and Berlin.
The deal, which will require Swiss banks to deduct taxes from German clients and transfer the tax revenues to Berlin — thus allowing the clients to remain anonymous — is to be voted on by the upper house of the German parliament on Friday.
It is expected to be rejected though, since a majority of the Bundesrat has voiced opposition, deeming the deal is too lenient on tax evaders.
Rohner said it would be a shame if the deal did not go through.
"In my view, it would be a very good agreement for all those involved," he said, stressing the deal would help smooth relations between the two countries which have become tense amid allegations that Swiss banking practices are helping Germans hide billions of euros.
The Bundesrat should pass it as quickly as possible, he said, pointing out that "every day (without a deal) possible tax claims are slipping away."
But if the treaty is rejected, Credit Suisse does not intend to allow tax evaders to remain on as clients, he stressed.
If potential clients refuse to report their assets to the tax authorities in their countries, "the bank will clearly tell them that it does not want
their business," Rohner said, adding that the bank would also ask existing clients to leave if they did not declare their assets.
If ratified, the tax deal is set to take effect on January 1st next year, and will entail taxation rates of between 21 and 41 percent on German assets held in Switzerland.
Switzerland has reached similar deals with Austria and Britain and is negotiating deals with Greece and Italy