The Employer
The first question that needs to be answered is, does the activity of the employee or employee(s) in a different country from the country that the company is incorporated in, and traditionally trading from, constitute a Permanent Establishment (“PE”)?
The clue is in the name – it needs to be permanent – i.e. not temporary. Temporary is often considered to be less than 6 months – although things like Covid allow you to increase this period.
It needs to be an “establishment”. e.g. an office, a place of business… somewhere you can point to and say – that is where the business is.
OR
It could be that the activity of an individual ALONE, even if they are working from home, or variable locations, is substantial and significant enough that the country deems they can tax it regardless.
A particular issue is “sales activity”. Someone generating sales in a country is likely to be considered creating value in that country and therefore it is a taxable activity on the company. A management team, or senior staff is also generally considered a PE.