Things like this exist in Sweden, and they aren't a problem.
When you sign on to the government tax website (or mobile app, or whatever) you are presented with all the numbers they have for you, which means whatever your employer(s) and bank(s) have reported on you. (Same as in the US, the IRS knows these things already, they just don't tell you what they know).
If you are fine with that, you sign it, and it's done. Denmark has their system setup so that if you do nothing, it's the same as accepting.
But if you have more information, if you have deductions to make, and there's plenty of those in Sweden as well, you just fill in the information in the very nice government tax app, and you're done.
When you sign on to the government tax website (or mobile app, or whatever) you are presented with all the numbers they have for you, which means whatever your employer(s) and bank(s) have reported on you. (Same as in the US, the IRS knows these things already, they just don't tell you what they know).
If you are fine with that, you sign it, and it's done. Denmark has their system setup so that if you do nothing, it's the same as accepting.
But if you have more information, if you have deductions to make, and there's plenty of those in Sweden as well, you just fill in the information in the very nice government tax app, and you're done.