Voters in Geneva have come out narrowly in favour of imposing a "wealth tax" on those whose personal fortune exceeds SFr1.5 million ($960,000).
Companies that post profits of more than SFr1 million a year would also be hit by the levy, which would only be enforced once the unemployment rate tops two per cent. In April, the figure stood at 4.5 per cent
The proposal, which was submitted by a left-wing coalition, was passed by a margin of just 730 votes - 53,350 to 52,620.
An estimated 4,500 multi-millionaires live in the canton and the new wealth tax is expected to raise an extra SFr250 million a year.
Geneva and neighbouring canton Vaud are a favourite place of residence for wealthy individuals seeking to avoid high taxes in their own countries.
Vaud/Geneva merger rejected
In another poll, voters in Geneva and Vaud have overwhelming rejected a proposal to merge their two cantons. Some 80 per cent of Genevans and 77 per cent of voters in Vaud turned down the proposed marriage.
Voters were widely expected to throw out the initiative, even though its backers had been at pains to tout the benefits of a union, which included creating a French-speaking region powerful enough to counterbalance mighty Zurich.
The twin initiatives were proposed by the Union Vaud-Genève, an association created four years ago to promote the idea of a merger. It said that for ordinary people the region already exists - every day, 17,000 people commute between the two cantons.
"I'm satisfied with the result," said François Cherix, president of the Union. "Our aim was to pass the 20 per cent threshold in both cantons."
Many supporters and opponents acknowledged the arguments in favour of a merger, not least because it would have cut public spending by as much as 13 per cent.
But on the day, the arguments of the two cantonal governments prevailed. They said a merger would infringe on the "unique historical and institutional realities of the two entities, as well as their different political cultures".
There were also fears that thousands of public employees would have been made redundant, as a result of a merger.