Credit Suisse has said its offices in London, Paris and Amsterdam have been visited by local authorities in connection with unspecified client tax issues.
The Swiss bank said the contacts took place a day earlier, and emphasised its "strategy of full client tax compliance".
It said Credit Suisse will next month start a programme of automatic information exchanges with European countries.
Credit Suisse spokeswoman Anna Sexton declined to comment further.
Swiss banks have long been a focus of international efforts to clamp down on tax evasion.
In December, the Paris-based Financial Action Task Force said Switzerland had achieved "good results" in fighting money-laundering and terrorism financing, but called on it to strengthen its compliance controls, boost scrutiny on the use of cash and share information more with foreign authorities.