Would "ex post facto" apply to tax deduction laws?

Question

Yesterday I had a discussion with my colleague.

This year I am traveling rather large distances for work. My colleague asked me how I can bear the costs of travel. I told her it is ok, because the government allows me to deduct a large part of my travel costs from my taxes.

My colleague warned me that she has heard that the government will revoke these rules, making it no longer possible to deduct as much of my travel costs from my taxes.

Her argument was that since my taxes for 2019 will be done in april of 2020, the government could, at any point before that date, change the rules so that I may no longer be able to deduct my travel expenses.

I argued that rules could only apply to travels/work that occurred after said rules were implemented, and could not apply retroactively.

Norway has an "ex post facto" clause in its constitution against retroactive laws.

Is my reasoning correct?

Answer 1

Article 75 says that

It devolves upon the Storting: (a) to enact and repeal laws; to impose taxes, dues, customs and other public charges, which shall not, however, remain operative beyond 31 December of the succeeding year, unless they are expressly renewed by a new Storting

Article 97 says that "No law must be given retroactive effect" . The combined effect of these provisions is that any changes in the law effected this year could apply to tax years after 2020 but not including 2019. So the law as written supports your understanding. Skatteetatten seems to agree since the rules are listed as covering 2019.