Dear Sirs

I am a US resident since a couple of year .

I established a company in San Diego in 1993 and after a number of years I asked the green card that I received in 2008.

I have a company in Italy too and I am regularly paying my taxes in Italy and in USA.

My CPA brought to my attention a doubt about my Italian taxes with regards to the US ones.

I am already paying in Italy the highest bracket but in according of Italian rules they are not split like in USA in between Federal and State

The question of my CPA was . The State of California may require a “double” taxation , so a taxation on my Italian income because it is not evident that part of the taxes I am paying are going to the “State” …

I would like to ask your help to find where I can get better details about the correct rules for the taxation in the two countries.

On your return, you must report your world wide income.
So you will report your Italy income. For the taxes paid in the foreign country, you will claim credit for taxes paid in the foreign country by filing Form 1116 or can file form 2555 Foreign Earned Income Exclusion.
Another filing requirement is Form TD F 90-22.1 and also Form 5471.

Your U.S. Tax Return: U.S. Citizen or Resident with Foreign Income (http://taxipay.blogspot.com/2008/03/us-citizen-or-resident-with-foreign.html)