Voters in Geneva look likely to decide if share dividends should be taxed in the same way as income.
Campaigners say the tax exception on dividends costs the canton CHF 120m a year.
6,600 signatures have been collected, more than enough to force a vote – but they have to be validated yet.
It’s the second time the move has been tried, but the first initiative was rejected by the Council of State as it was so badly worded it would actually have meant shareholders would have paid les tax.