In Norway, you these days don't even need to sign if you have nothing to amend (we started with electronic delivery many years ago, then SMS signing if you had

In Norway, you these days don't even need to sign if you have nothing to amend (we started with electronic delivery many years ago, then SMS signing if you had nothing to change, up to some years ago when not doing anything is an implicit signing of the prefilled tax return). If you do change anything, what you sign is something akin to "These numbers and information are given to the best of my abilities". AFAIK, you basically have 10 years to correct mistakes, and this goes both ways.