I have a house in another state that I own with my son. I do not have enough deductions to claim the taxes on my federal but have claimed it on my state. Can he claim it on his federal with me having claimed it on my state?

If you jointly own the house, and it qualifies as a second home for both of you, then you should split any deductions between you and your son based on who actually paid for the deductible expenses. If you try to play the game of listing different amounts on your state versus federal returns, I think you are opening yourself up for some nasty future dealings with the tax authorities.

Did you receive a 1098 Form from your mortgage lender, and if so whose name(s) are shown? From IRS Pub 936: Publication 936 (2007), Home Mortgage Interest Deduction (http://www.irs.gov/publications/p936/ar02.html#d0e749)

More than one borrower. If you and at least one other person (other than your spouse if you file a joint return) were liable for and paid interest on a mortgage that was for your home, and the other person received a Form 1098 showing the interest that was paid during the year, attach a statement to your return explaining this. Show how much of the interest each of you paid, and give the name and address of the person who received the form. Deduct your share of the interest on Schedule A (Form 1040), line 11, and print “See attached” next to the line.

Similarly, if you are the payer of record on a mortgage on which there are other borrowers entitled to a deduction for the interest shown on the Form 1098 you received, deduct only your share of the interest on Schedule A (Form 1040), line 10. You should let each of the other borrowers know what his or her share is.