Parliament has decided to tighten sanctions for violations of Swiss banking secrecy laws.
The Senate on Monday increased prison sentences to a maximum of five years for bank employees who pass on stolen customer data. The law now also applies to third parties.
The other parliamentary chamber, the House of Representatives, approved the amendments in September.
Current law has only applied to bankers found guilty of stealing and passing on data. They have faced jail terms of up to three years.
Supporters, including centre-right and rightwing parties, said stricter rules would have a preventive effect and boost confidence in Switzerland’s finance industry.
However, opponents from the left argued the amendment was unnecessary as the government had agreed to adopt the automatic exchange of tax information in line with the Organisation for Economic Co-operation and Development (OECD).
The tax authorities in the country’s 26 cantons had also come out against tighter laws, saying they could lose access to data of suspected tax cheats.
Switzerland has a three-tier tax system which leaves wide-ranging autonomy to the cantons.
swissinfo.ch and agencies