Taxes are paid continuously by my employer on each salary payment, and if at the end of the year it turns out I paid too little, I get a bill, and if I paid too much, I get a return to my bank account.
It's part of a bigger question I have been pondering recently. My sense is that in the 80s/90s the US tax system was much more efficient than the UK/Ireland/Scandinavia/German/Baltics system but somewhere along the line we learned their lessons and overtook them in terms of efficiency. (I suspect it's a bit like the Beta/VHS thing).
Even running a small company taxes in the UK is (honestly) not too tricky when it comes to this stuff - I'm sure it's even easier in a flat tax place like Estonia (take 20%, send it electronically to government, go back to work.).
I can only imagine how painfully complex it is in the US - and the amount of time an entrepreneur would spend dealing with it instead of building stuff.
Having been in the states a number of times in the last few years, I have been pretty shocked about the amount of bureaucracy that gets in the way of even very basic stuff - simple transactions, employee visas, lack of credit/eletronic payments for stuff etc etc