Thanks Gabriel!! I will Take a look at !!Google does not pay federal or state taxes for you. You will be required to file a tax return when you earn over $400 in a year. When using Google AdSense or by joining a YouTube network, you are considered an independent contractor and not an employee of the network or of Google.
You may still need to file a tax return even if you do not earn over $400 in a year. More details can be found at irs.gov/Individuals/Self-Employed
Above info is for 2014 tax year, might change for 2015 tax year.
Where are you living? I could have sworn you were from Italy and if so the tax rules over there may be different.