It sounds like just semantics to me. He paid for half the house.
No income tax or gift tax on his portion of the mortgage payments. Again, you're just sharing expenses. If he's going to claim a deduction for his share of the mortgage payments, though, it would be better if he wrote a check directly to the lender, for purposes of supporting the deduction in case the IRS questions it, especially since his name is not on the Form 1098. But that raises another issue --
The mortgage lender might object to your putting your brother on the title, since that reduces your ownership interest, and your brother is not obligated on the mortgage. The mortgage probably says that the full balance is due immediately if you change the ownership of the house. You have to be careful not to trigger that. This is not a tax question, and is outside my area of expertise. Maybe it's possible to add your brother to the mortgage as well as the title. Before you do anything, you should discuss your plan with a real estate lawyer or a mortgage broker, or both.
