A number of Swiss regional banks have agreed to work with US officials as part of a crackdown on wealthy Americans who evade paying tax on money hidden in Swiss banks accounts.
The latest banks to have agreed to cooperate with the US include Banque Cantonale Vaudoise (BCV), Banque Cantonale de Geneve (BCGE), St. Galler Kantonalbank, Zuger Kantonalbank, Luzerner Kantonalbank and Graubuendner Kantonalbank.
BCV's subsidiary Piquet Galland & Cie SA and St. Galler KB's subsidiaries Hyposwiss Privatbank Zurich AG and Hyposwiss Private Bank Geneve SA are also joining the deal.
The cantonal banks who agreed to take part in the US crackdown noted that they had never focused on acquiring US-based clients, but said they are not sure whether all customers had met their tax obligations in the US.
The move by the Swiss banks comes days after the US Department of Justice warned that banks found to be complicit in US clients' tax evasion, will face penalties of up to 50% of untaxed assets managed for those clients.
Several famous Swiss banks, including Credit Suisse and Julius Baer, are already undergoing formal criminal investigation in the US.
About 100 banks are expected to take part in the scheme by the end of 2013.
Growing Number of Swiss Banks in US Scheme
The US and Switzerland earlier agreed on a new programme to hand over account information of tax evaders.
The deal will allow around 100 second-tier Swiss banks to pay penalties to avoid or defer prosecution. It also requires them to disclose cross-border activities and account information about US customers.
The Swiss banking industry has traditionally been unwavering over its infamous secrecy provisions, that are upheld by the country's constitution.
Switzerland is thought to have attracted more than $2tn (£1.3tn, €1.5tn) in offshore deposits, according to certain estimates.
US authorities have focused on Swiss bank accounts after revelations emerged about $20bn of US client money hidden from the IRS by private bankers at UBS.
Since deferring prosecution of UBS in 2009, the US has doggedly pursued other Swiss deposit takers.
The US Foreign Account Tax Compliance Act was enacted in 2010 to claw back tax on assets hidden by wealthy US citizens in offshore tax havens like Switzerland.