In legislation that will come into force on November 1st, the Bern-based Money Laundering Reporting Office (MROS) said that Swiss authorities will be able to release the numbers of bank accounts opened in the country to foreign investigators.
A day earlier, Switzerland, widely considered a tax haven and long criticized for its secretive banking culture, signed an international agreement to exchange information among more than 60 countries aimed at exposing tax dodgers.
That agreement still has to be ratified by parliament.
Swiss authorities have come under pressure from the international community to clamp down on the concealment of illicit funds and tax evasion in the wake of both the global financial crisis of 2008 and subsequent eurozone debt crisis.
Ordinary people facing increasing financial pressures, often facing higher taxes to cover the costs of the crises, were outraged by revelations of tax evasion and avoidance by corporations and wealthy individuals.
The revised legislation, which incorporates recommendations form the Financial Action Task Force on money laundering (GAFI), will make it easier to communicate financial data abroad — except in cases where national security is threatened.
The MROS will be able to release banking information only if someone is formally investigated for money laundering.
And Switzerland will still refuse its cooperation in cases stolen bank data are presented to be used in an investigation, the government decided on Wednesday, dropping an earlier proposal to allow their usage.
The banking sector had cried foul at the measure, which relates to CDs of data stolen by employees of Swiss banks who then sell them to foreign tax authorities, notably in Germany, where they are used to track down suspected tax cheats.
But the government did relax a rule that said bank customers being investigated for fraud had to be informed immediately.
Now, with only certain exceptions, they will be only informed once their data has been transferred to investigators.
Meanwhile, Tuesday's tax evasion agreement allows for simultaneous controls to track fraud so as to harmonize cross-border investigations.
These have in the past been hampered by the complex routes used to hide funds, coupled with obstructionism on the part of some national authorities.
Parliament will this winter examine further legislation that seeks to modify the legal definition of tax fraud and tax evasion.
According to Swiss law, tax cheats could simply have "forgotten" to declare their assets, meaning tax evasion is not classed as an offence punishable by law, except if it is carried out using forgery, which does carry a maximum three-year prison sentence.
Tax fraud, meanwhile, is seen as a deliberate act.
Lawmakers will review the definition of both acts, whose ambiguity tax cheats have played on to avoid declaring funds.