Huh, I went to check - we did it in 2003 (for vat and income tax iirc, ofc they expended it since, nowdays only courtroom stuff doesn't have online admin systems).

Prior to that you just got the (already filled out) income tax form in the mail - if everything was ok that was usually it. In case you still owed, it included the bill, it they owed you they wired the money to your bank.

If the tax forms were incomplete for some reason (or just not optimised between the members of the same family) you could fill in what they missed (like literally with a pen) & send it back (for them to verify & return it to youb revised).

(This system still works so folk who prefer to do it via paper can do that.)