30% if there’s no tax treaty. Treaties trump laws (if ratified). So you’ll have to read through each treaty with your employees’ country to see what needs to be

30% if there’s no tax treaty. Treaties trump laws (if ratified). So you’ll have to read through each treaty with your employees’ country to see what needs to be withheld. So for OP, for operational simplificity, a domicile with the least number of treaties would be best (but possibly horrendous for tax efficiency).