H1B holder basic salary is paid in home country by home country employer who is in joint venture with H1B sponsor. Visa holder receives per diem amount in the US. He has not received any W2 or the like for 2005? What is his income for filing? Can he exclude the per diem payment? He is not from a tax treaty country. Any thoughts ?

Even though the salary is paid in home country, it was earned in the U.S.

Hence, the salary is subject to U.S. taxation.

The per diem is a reimbursement for expenses. If properly accounted for, it is not taxable. If paid with no accounting, it is fully taxable.