I am buying a house with a friend. His name is on the loan because my credit was bad. My name is on the deed and on county tax collector's records. Can I still claim 1/2 the interest. My friend is not filling taxes at all. I wonder if I can claim all the interest? Please help.

According to IRS Publication 936: Home Mortgage Interest Deduction:

"You must be legally liable for the loan. You cannot deduct payments you make for someone else if you are not legally liable to make them. Both you and the lender must intend that the loan be repaid. In addition, there must be a true debtor-creditor relationship between you and the lender."

The short answer is that you qualify to deduct every dollar of interest you pay regardless of the arrangements.

(The statement that Coldfuse is quoting refers more to derititive investments where the line between long-term loan and capital ownership becomes blurred. That's why it mentions "debtor-creditor relationship" as opposed to "company-owner relationship".)