In the UK it's possible to see a running estimate of your current tax position and the estimate for the end of the year. HMRC issues you a tax code which is use

In the UK it's possible to see a running estimate of your current tax position and the estimate for the end of the year. HMRC issues you a tax code which is used by your employer to determine how much tax they should be deducting each pay period. This means that in most cases you get no nasty surprises at the end of the year. I've always found the US tax system bizarre.