Our parent company owns a company in Germany. They are looking to bring over a German National (Using an L-1 Visa) to work at our corporate office here in the U.S. for approximately 18 months. He will apply for a social security card/number. My question is:
Once he obtains a SSN I will set up payroll information in my system. Will he have to pay income taxes; federal, FICA and state, if applicable? I'm confused because I thought the U.S. had a Tax treaty with Germany. Please help!

Thank you!

The tax treaty only covers certain taxes, not necessarily employment taxes. Here is the website which will direct you to the germany/us tax treaty in detail.

www.irs.gov/businesses/international/.../0,,id=96739,00.htm