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The revenue you get from Google is Income for you. That means you have to pay income tax (percentage depending on your personal situation).
The $600 treshold may be important for US based publishers, but here you simply bring your check to the bank and pay those ridiculous high fees (I am paying €23,- for each foreign check).
The treshold you may want to worry about is €25.000,- then you will be subject to anti-money-laundry monitoring (Geldwaeschegesaetz).
However, being a good citizen you probably have your company registered with the authorities and therefore have a Tax-ID - leave the worries to your accountant and keep building your business :,)