It’s done automatically in the US too, as far as it can be. Income tax is withheld from our paychecks based on a form we fill out, where we say if we’re single or married and how many dependents we have. But the formula used to figure out how much to withhold for tax can’t anticipate things we do during the year that change our taxes - for example, charity donations, investment income, or using our own cars for work purposes. So we have to do a final figuring.