Tax accounting is one of the most difficult task for every accountant and even more customers. It really depend in which country you are living in and the multiples type of incomes you get.
In some countries like in the UK you may be able to claim a tax refund if you worked less than a full tax year. In USA, you need to file federal and state taxes separately. The US Tax system is one of the most confusing and difficult system to follow.
2008 2009 Income Tax filing has officially begin on 15th January 2009 in USA.