For tuition deduction up to $4,000 (in 2007), I think you have to be a US resident (by definition of tax law, not immigration law). If you are F-1 or H-1, for the first 5 years, you're a non-resident alien. After that, you can file tax returns just like other greencard holders or US citizens. Also $4, 000 is a deduction from your income not a tax credit.