[tremon]

(and this threshold may vary from country to country)

To be more specific: this depends on treaties between the country of residence and the country of employment, so it can vary for every combination of countries. It may even mean that taxes are due in both countries (double taxation), and getting a tax waiver in one of them may require legal proceedings and/or expensive accountants.

[Bouncingsoul1]

It may even depend how close you are to the border. E.g. between germany-austria-swiss, you have grenzgänger status if you are within 30 km of the closets border, which may influence your social/ healthinsurance and your income tax