A different institution from what? If all banks, employers and other institutions are required to send the info to the tax authority, the only "other" things yo

A different institution from what? If all banks, employers and other institutions are required to send the info to the tax authority, the only "other" things you need to fill in is basically income made abroad. But most people obviously don't have foreign income or assets, so a tax calculation should be 100% correct and simply a matter of accepting? The Tax authority should also have a very good guess of all possible deductions/credits, so that can be filled automatically too.