When I take work-related travel — fieldwork or a conference — I get paid a per diem to cover my meals (accommodation costs are covered separately). The per diems vary by country, but are otherwise fixed across the Norwegian public sector, paying a PhD student and the university’s rector the same amount.
So far so fair. But then it gets weird: if I stay in a hotel, the per diem is tax free; if I stay in a guest house or hostel (without cooking facilities), over half of the per diem is taxable. Since the cost of the food I buy during the day does not depend on the type of accommodation I use at night, I cannot imagine what the purpose of this rule is. I also don’t imagine that the politicians and senior civil servants who write these regulations would stay anywhere other than a hotel (*****) when travelling for work, and so are not affected by it.
If I stayed with a friend or somewhere I could theoretically cook, then even more of the per diem is taxable.
With a marginal tax rate of 45%, the tax on the per diem amounts to a respectable amount of money after a week-long conference. This make the tax rule a perverse incentive to stay in an expensive hotel (costing my project more) rather than staying somewhere cheaper.