All I have to add is my deduction items, and BAM! it's done. Also, we automatically pre-pay our taxes because it is calculated and payed for by all employers.
Every year, they add some improvements to the entire system. They basically prefill your entire income and capital. Including stocks, dividends and other things. The only things you need to fill in yourself are some of your deductions (there are some which are prefilled as well).
They open the filing of taxes every year on march first. And every year there are lots of people who fill it in on the first day. This year there was even someone who handed their taxes in 18 seconds past midnight.
At least the Dutch ones tend to just be click-click-check-done, so it's not too bad. But it was sad moving to filing annual tax returns from a much simpler system.
This is generally the case as long as you do not deviate. In the past I requested to delay having to file taxes and they rejected my request because I did not have to. The 'but' is that as soon as you screw up, or one of your bosses screws up, or you forgot to file something, you have to file from that point onward.
It is always a good thing to do anyways as you might get money back.