In most of EU, the tax authority first asks you nicely to fix your mistake, and only if you don't, they confiscate the owed amount plus a small fine (given that it's your first offense and they don't see it as intentional fraud).

I used to have my life in serious disorder and they confiscated the owed tax three times from me. Never got fined more than $100, though I had to call and apologize the second and third time to have it reduced from ~$500.