It is the tax office's responsibility to calculate how much you should pay in tax, but they cannot do this before they know how much you have earned. Your employer reports how much you have earned in the past year to the tax office. Then, the tax office sends you a pre-completed tax return and asks you to confirm that the information about income and deductions etc. is correct, or to correct the information if necessary. If you need more information, you can read the guidelines to the tax return. If you have no changes to make, you do not have to submit your tax return.
Once the tax assessment office has processed your tax return, you will receive a tax settlement notice. If you are due a tax refund, the money will be transferred to your bank account. If you have paid too little tax, you have to pay the underpaid tax. Changes can be made online. It is also possible to submit a corrected tax return on paper.
For more information about the tax return for 2009: