Withholding tax according to the ACT
The withholding tax with a compensatory effect is levied at source at a flat rate and transferred to the tax authority of the partner state. It promotes the tax honesty of clients of Swiss paying agents resident abroad. Switzerland has concluded withholding tax agreements with the United Kingdom and Austria for this purpose.
Not all sites have been translated to english. Please refer to the german, french or italian original version for additional information.
Link
Article 3 of the Federal Act on International Withholding Tax