If approved, the measures will end Switzerland's free movement of people agreement with the European Union.
Fiercely independent Switzerland is not a member of the EU, but has adopted large sections of EU policy.
Brussels has already warned the Swiss that they cannot just choose the aspects they like.
The vote comes amid increasing debate across Europe about migration and the impact of free movement of people.
Analysts had expected a tight race, but the BBC's Imogen Foulkes in Switzerland says it appears to be incredibly close. » | Sunday, February 9, 2014
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