My hubbie worked as a freelancer through an agency (as his employer doing his payroll ect.) They paid him 20k per year as expat allowance. His contracts were just over 1 year each time. He did this for 5 years in Zug and it was allowed. Other colleagues in Zürich working through the same agency for the same client (same contract terms and durations) had their allowance disallowed after one year, so it could depend on the Kanton you live in. We have waited for this decision to come from the Zug tax authorities but it never has. We rent out our UK flat and declare everything on our tax declation too.